G.C.E. A/L Examination June - 2016 - AGARAM

Grade:- 13 (2016) - June - 2016 1 Physics - I

01) In this equation, if h is the Planck constant, f is frequency and V is velocity, then A, B

respectively denote

(1) force, mass

(2) energy, mass

(3) frequency, energy

(4) work, frequency

(5) force, frequency

02) What is the intensity of heat radiation (in Wm-2) at a point 1m from a point that radiates heat at a

rate of 50W?

(1)

(2)

(3) (4)

(5)

03) The ratio between the amplitudes of two waves is 9:1. What is the ratio between the maximum and

minimum sound intensities caused by the interference of these two waves?

(1) (2) (3) (4) (5)

04) A man watches a stone at the bottom of a water tank from above. If the height of the water column

in the tank is h, at what depth will the stone’s image be? (the refractive index of water is n)

(1) (2) (3)

(4)

(5)

05) The length of an iron rod in a Kundt’s tube is 1m. If the frequency of the standing wave formed here

is 2500Hz, what is the speed of sound in the iron rod?

(1) (2) (3)

(4) (5)

06) The ratio of turns in the coils of a step up transformer is 250:1. This transformer has 90% efficiency.

If the current through the primary coil is 250A, what is the current through the secondary coil?

(1) (2) (3) (4) (5)

07) A ring of charge with radius 0.5m has 0.002π m gap. If the ring carries a charge of +1 C, the electric

field at the center is (

)

(1)

(2)

(3)

(4)

(5)

G.C.E. A/L Examination June - 2016

Conducted by Field Work Centre, Thondaimanaru

In Collaboration with

Zonal Department of Education Jaffna.

Time :- Two hours Grade :- 13 (2016) Physics - I

FWC


08) Which of the following statements about Ultrasound is not true?

(1) It moves with the velocity of sound.

(2) It has a higher frequency than normal sound.

(3) It cannot be heard by human ears.

(4) It has a lower wavelength than normal sound.

(5) It does not cause Doppler Effect.

09) The figure shows a uniform, solid, right circular cone kept in equilibrium with its vertex touching a

horizontal surface. This equilibrium is unstable. Which of the following statements is not suitable to

explain this?

(1) The position of the center of gravity is higher.

(2) The cone is symmetrical about its axis.

(3) The narrow part is kept in contact with the surface.

(4) Its potential energy is at a higher level.

(5) The couple which acts when the cone inclines slightly, will topple it

10) A driller with a power of P W is used to drill a hole in a copper block of mass M kg. The specific heat

capacity of copper is S Jkg-1K-1. 40% of the power is used to heat up the drill. What is the rise in

temperature of the copper block at time T s?

(1)

(2)

(3)

(4)

(5)

11) A sine alternating current with peak value flows through resistor R. What is the rate at which

heat is produced in the resistor R?

(1) (2)

(3) (4)

√ (5)

12)

Four positions of a heavy rod of weight w are shown in the above figures. In which of these figures

is balance possible?

(1) (2) (3) (4) (5)

13) In the circuit shown in the figure, the charges

stored in C1 and C2 respectively are,

(1)

(2)

(3)

(4)

(5)

Rope Rope

Smooth

wall

Smooth

wall

Smooth floor

Fig - Fig - Fig -

Fig -

pivoted


14) What is the single logic gate that is equivalent to the combination of gates given below?

(1) AND gate (2) OR gate (3) XOR gate (4) NAND gate (5)NOR gate

15) Two artificial satellites, A and B, revolve around the Earth.

The mass and the radius of orbit of A are twice that of B.

What is the ratio between the linear velocities

?

(1)

(2)

(3) √

(4)

√

(5)

16) 1 mol of a monatomic ideal gas is taken from A

to B through path ACB. If the temperature at A is

T0, what is the amount of heat absorbed by the

gas during the process ? (for a

monatomic gas,

and

)

(1)

(2)

(3)

(4)

(5)

17) Two balls, A and B are thrown from the same spot at the same time. A is thrown vertically upwards,

while B is thrown with an angle of 30o from the vertical. If the two balls reach the ground at the

same time, what is the ratio between the velocities with which each ball, A, B, is thrown?

(1) √ (2) √ (3) √ (4) √ (5)

18) A ring of radius r and mass m, which is made from a thin wire, is placed horizontally within a liquid

of surface tension T. What is the minimum force required to tale this ring out through the liquid

surface? (the contact angle is zero)

(1) (2) (3)

(4) (5)

B

A

C

Pressure

Volume


19)

The operational amplifier shown in the diagram works with a supply of +15V - -15V. What is the

output voltage, Vout, of the circuit?

(1) (2) (3)

(4) (5)

20) A hemispherical portion has been removed from a solid cylinder of

radius r. the mass and volume of the remaining part of the cylinder

is m and v respectively. As shown in the figure, this cylinder is held

by a string in a liquid of density ρ, with its upper surface at depth h.

What is the force exerted by the liquid on the lower surface of the

cylinder?

(1)

(2)

(3)

(4)

(5)

21) If the wavelength of maximum intensity of the sun’s radiation is 510nm and that of another star is

350nm, what is the ratio between the surface temperatures of the sun and the other star?

(1) (2) (3)

(4) (5)

22) A compound microscope has two converging lenses of focal length 3cm and 5cm. A man with least

distinct vision at 25cm observes an object kept 4cm in front of the objective. The microscope is

adjusted so that the final image is at infinity. What is the separation of the lenses?

(1)

(2)

(3)

(4)

(5)


23)

Sphere A of mass m, moving with velocity V, collides with sphere B of mass nm, travelling in the

same direction with velocity kV. After the collision, if sphere A comes to rest, what is the velocity of

sphere B?

(1) (

) (2) (

) (3) (

)

(4) (

) (5) (

)

24) A cube of side length a, moves with velocity V, along a smooth horizontal

surface, as shown in the figure. It collides with an obstacle at point O. What is

the angular velocity of the block after the collision? (The moment of inertia of

the block about a perpendicular to plane horizontal axis through one of its

vertex is

ma2)

(1)

(2)

(3)

√

√

(4) √

(5)

25) The diagrams show particle movement in an air column when a stationary wave exists in the

column. The first diagram shows the displacement of some particles at one instant and the second

diagram shows the displacement of particles half a cycle later.

What is the length L if the column in terms of the wavelength λ, and at which position within the

column does the pressure change by the largest amount?

Length maximum pressure change at

(1)

node

(2)

antinode

(3)

node

(4)

antinode

(5)

antinode


26) In a helium-neon laser, helium atoms collide with neon atoms and excite them. This produces a

population inversion which allows stimulated emission. Which neon energy level diagram correctly

shows the excitation of the neon atoms by the helium atoms, the spontaneous infra-red emission

from the neon, and the stimulated emission of red light?

27) In a prism shaped network made of nine conductors, each having 5Ω resistance, what is the

equivalent resistance between the point A and B?

(1)

(2)

(3)

(4)

(5)

28) The figure shows a metal ball of volume 400cm3, floating in a

mercury-water interface in a vessel. Half of the ball is immersed in

mercury. What will happen if liquid X, with density 9400kgm-3 is

poured into this vessel? (The density of mercury is 13600 kgm-3 and

that of water is 1000 kgm-3)

(1) The ball will float with 300 cm3 in liquid X and 100 cm3 in mercury.

(2) The ball will float with 300 cm3 in liquid X and 100 cm3 in water.



(5) The ball will float with 200 cm3 in liquid X and 200 cm3 in mercury.

spontaneous emission

stimulated emission

(1) (2)

(3) (4)

(5)


29) In a practical Wheatstone bridge circuit, when one more resistance of 100Ω is connected in parallel

with unknown resistance x, then the ratio of

becomes 2. is the balance length. AB is a uniform

wire. Then the value of x must be

(1) (2) (3) (4) (5)

30) A milli-ammeter of range 10mA and resistance 9Ω is

joined in a circuit as shown in the figure. The meter

gives full scale deflection, when current in the main

circuit is I, and A and D are used as terminals. The value

of I is

(1) (2) (3) (4) (5)

31) Two stones are thrown vertically upwards at the same time with velocities u1, u2 (u2>u1). They reach

the ground in 6s and 10s respectively. Which graph shows the change of difference in

displacement, Δx, of the two stones during the journey with time? Consider that the stones do not

bounce on hitting the ground.

(1) (2) (3) (4) (5)

32) The figure shows a light ray entering normal to a surface of a glass right prism, of which one angle is

60o. the emergent ray is

(1) (2) (3) (4) (5)

Copper strip

Copper strip


33) A bungee jumper has 24kJ of gravitational potential energy at the top of his jump. He is attached to

an elastic rope which starts to stretch after a short time of free fall. The values of gravitational

potential energy, elastic potential energy and kinetic energy are given for the top and bottom of

the jump.

Gravitational potential

energy (kJ)

Elastic potential

energy (kJ)

Kinetic energy (kJ)

Top

Bottom

Which row of the table below shows possible values of these three energies when the jumper is

halfway down? Losses of energy through air resistance are negligible.

Gravitational potential

energy (kJ)

Elastic potential

energy (kJ)

Kinetic energy

(kJ)

(1)

(2)

(3)

(4)

(5)

34) As shown in the figure, a uniform rod has a wooden section and a solid rubber handle. The length of

the handle is and the length of the wooden section is 4 . The rod balances at a distance of 2

from the rubber end. What is the ratio between the densities of rubber and wood?

(1) (2) (3)

(4) (5)

35) The least distance of distinct vision of an old man is 60cm. He can see distant objects clearly. If the

distance between his eye lens and retina is 3cm, what is the least focal length that his eye lens can

achieve?

(1)

(2)

(3)

(4)

(5)


36) A fixed amount of ideal gas has pressure P and volume V. The graph shows the variation of

with V

at a constant temperature. The amount of gas and the thermodynamic temperature are both

doubled. Which line will be produced?

(1) A (2) B (3) C (4) D (5) E

37) Two blocks of masses 5kg and 3kg, are placed on a horizontal surface as shown in

the figure. The coefficient of friction between the two blocks is 0.5. The coefficient

of friction between the 5kg block and the surface is 0.7. What is the maximum

horizontal force that can be applied to the 5kg block, so that the two blocks move

without sliding against each other?

(1) (2) (3) (4) (5)

38) A, B, C, D, P and Q are points in a uniform electric field. The potentials at these points are

, , and . Find the electric filed at P.

(1)

(2) √

(3)

√

(4) √

(5) √

E


39) A small lead ball falls through a liquid with a speed of 10 cm s-1. If the liquid exerts an upward force

on the ball that is equal to its effective weight. What is the speed with which the ball will move up?

(1) (2) (3)

(4) (5) ;.

40) Two particles, each of mass m, are joined by a light, inextensible

string of length 2a, as shown in the figure. This system is kept on a

smooth surface such that the string remains taught.

A small, constant horizontal force F is applied at the centre of the string, P, causes the two particles

to move towards each other. When the distance between the two particles is , what is the value

of acceleration?

(1)

√ (2)

√ (3)

(4)

√

(5)

√

41) The figure shows a circuit that may be used to compare the

resistance R of an unknown resistor with a 100Ω standard. The

distances from one end of the potentiometer slider wire to the

balance point are 400 mm and 588 mm when X is connected to Y

and Z respectively. The length of the slider wire is 1.00 m. What

is the value of resistance R?

(1) (2) (3) (4) (5)

42) The primary coil of an ideal transformer has 200 turns and is connected to a 15V r.m.s supply. The

secondary coil has 3200 turns and is connected to a resistor of resistance 120Ω, as shown in the

diagram. What are the possible values of the secondary voltage, the secondary current and the

mean power dissipated in the resistor?

Secondary voltage

(V r.m.s)

Secondary current

(A r.m.s)

Power dissipated at the resistor

(W)

(1)

(2)

(3)

(4)

(5)


43) 3/5th portion of a glass vessel is filled with mercury. The coefficient of volume expansion of the glass

and mercury are 9×10-6 oC-1 and 18×10-5 oC-1, respectively. The coefficient of apparent volume

expansion of mercury is

(1)

(2)

(3)

(4)

(5)

44)

A non-uniform thin rod AB of length 1m and mass 2kg is hung using 2 spring balances as shown in

figure (1). When a 2kg mass was hung a distance from A, the two balances showed different

readings. The graph shows the readings of X and Y, when the 2kg mass is hung at different values of

a while keeping the rod horizontal. The distance of the centre of gravity of the rod from A is

(1) (2) (3) (4) (5)

45) In the given circuit, when key K is open, reading of the

ammeter is I. If the key K is closed, which of the following

statements are correct?

(1) If , reading of the ammeter is less than .

(2) If , reading of the ammeter is greater than .

(3) If , reading of the ammeter will be zero.

(4) Reading of the ammeter won’t change.

(5) If reading of the ammeter will be zero.

46) A vessel contains a mixture of air and water vapour. at constant temperature its pressure, P, was

measured by changing it volume, V. Which graph best represents the P vs

curve that was

obtained?

Fig - Fig -


47) A “U” tube containing water and coconut oil is kept in a place with

still air, as shown in the figure. (Density of water - 1000 kgm-3,

density of coconut oil - 800 kgm-3, density of air - 1 kgm-3) To

maintain the liquid levels in the two arms of the “U” tube at the

same horizontal level,

(1) Air should be blown horizontally, in the direction into the

paper above the arm X with a speed of 20ms-1.

(2) Air should be blown horizontally, in the direction into the

paper above the arm Y with a speed of 20ms-1.

(3) Air should be blown horizontally, in the direction into the paper above the arm X with a speed

of 10ms-1.

(4) Air should be blown horizontally, in the direction into the paper above the arm Y with a speed

of 10ms-1.

(5) Air should be blown horizontally, in the direction into the paper above the arm X with a speed

of 5ms-1.

48) A screen and an object are separated by a distance . When a converging lens is placed between

them, the magnification by the lens was m. What is the focal length of the lens?

(1)

(2)

(3)

(4)

(5)

49) Two hollow spheres, A and B, of the same thickness but made of different materials, are filled with

ice cubes. The inner radius of A is twice that of B. When compared to the radius, the thickness of

these spheres can be neglected. The ratio between the time taken for the complete melting of ice in

A and that in B is 25:16. What is the ratio between the thermal conductivities of A and B?

(1) (2) (3) (4) (5)

50) A sound source placed very far from the observer emits a sound with frequency . The sound source

starts to move towards the observer with a constant acceleration . A short (just) while after the

source starts moving, what is the frequency of the sound perceived by the observer? (the speed of

sound in air is )

(1)

(2)

(3)

(4)

(5)

Grade:- 13 (2016) - June - 2016 1 Physics - II(A)

Part - II A

Structured Essay

Answer all four question on this paper itself

1) .

a) When a rigid object is taken far away from the Earth’s surface, will there be a change in its center of

gravity and center of mass?

Center of gravity – ........................................................................................................................

Center of mass – ........................................................................................................................

b) Figure (I) shows a uniform cylinder of length and diameter . Denote the

centre of gravity G, of this cylinder.

c) The cylinder is kept on a rough surface. The surface is slowly inclined.

Consider that slipping does not occur.

i) Figure (II) shows the position when the cylinder is about to tilt. Draw

the line of action of gravitational force at this instant.

ii) Find θ in terms of and , for the instant when the cylinder tilts.

................................................................................................................... ̀

...................................................................................................................

d) The leaning tower of Pisa, shown in figure (III) can be

roughly considered as a cylinder. The height of this

tower is 56m and the diameter of its base is 16m. This

tower is gradually approaching a state which will cause it

to fall. Upon reaching which value of θ will this tower

fall?

...........................................................................................

...........................................................................................

...........................................................................................





Three :- Three hours Grade :- 13 (2016) Physics - II

FWC

Fig -

Fig -

Fig - I


e) Figure (IV) shows a man horizontally pushing a 40kg

cylinder placed on a rough, horizontal surface.

i) Denote the horizontal forces acting on the cylinder and man, separately on the figures.

ii) The graph between the force, F, applied to the cylinder by man and the frictional force, X,

acting on the cylinder, was plotted as shown below.

Find the coefficients of static and dynamic friction between the cylinder and the surface.

Coefficient of static friction – ............................................................................................

............................................................................................

............................................................................................

Coefficient of dynamic friction – ............................................................................................

............................................................................................

............................................................................................

iii) For the man to continuously push the cylinder without slipping, what should be his least

weight? (Consider that the coefficient of friction between the man’s legs and the surface is 0.2,

and that the cylinder moves with a constant velocity)

..........................................................................................................................................................

..........................................................................................................................................................

Fig -


2)

a) Why is a steam generator used to heat the end X?

.................................................................................................................................................................

.................................................................................................................................................................

b) Should steam be sent in from above or below? Give reason.

.................................................................................................................................................................

.................................................................................................................................................................

c) Holes are made in the rod, a little mercury is poured into them, and then the thermometers are

kept. What is the reason for this?

.................................................................................................................................................................

.................................................................................................................................................................

d) Which property of mercury enabled it to be chosen for the action mentioned in part (c)?

.................................................................................................................................................................

e) What is the name of the part denoted by Z (shown within broken lines)? What is its use?

.................................................................................................................................................................

f) Why is cool water sent in the opposite direction to the heat flow?

.................................................................................................................................................................

.................................................................................................................................................................

g) The cool water tube is removed and an ice-water mixture is attached at that point. At stable state,

the ice dissolves at a rate of per minute. (The latent heat of fusion of ice is ) The

readings of the thermometers T1 and T2 are and , respectively. The distance between

these two thermometers is . The cross sectional area of the rod is . Find the thermal

conductivity of the material of the rod. (Neglect the heat loss to the environment)

.................................................................................................................................................................

.................................................................................................................................................................

.................................................................................................................................................................

Steam


3) a) What type of waves forms on a violin string? To which type do the sound waves reaching our ears

belong?

.................................................................................................................................................................

.................................................................................................................................................................

b) Even though the same not is played on a violin and a flute, the ear can distinguish them separately.

Which property of sound is identified here?

.................................................................................................................................................................

c) What causes this difference?

.................................................................................................................................................................

d) The figure shows a sonometer. The center point of the wire AB is vertically plucked. Is the wave

formed on the wire longitudinal or transverse?

.................................................................................................................................................................

e) How does the air in the sonometer box gain the energy to vibrate?

.................................................................................................................................................................

.................................................................................................................................................................

f) On the figure given below, draw the wave form of a wave that will have the maximum possible

wavelength on wire AB.

g) If a tuning fork has been given to you, explain how you will make the wire vibrate without plucking

it.

.................................................................................................................................................................

.................................................................................................................................................................

h) Give the equation for the wire’s fundamental frequency, , in terms of tension , length , and

mass per unit length of the wire .

.................................................................................................................................................................

i) If the mass of the wire , tension in the wire and the fundamental frequency

of the wire , then find the length of the wire.

.................................................................................................................................................................

.................................................................................................................................................................


4) The potential divider shown in the figure supplies varying potential (VXY) across its terminals X and Y. R

is a 5kΩ variable resistor with a sliding contact P. E is a 6V electric cell with negligible internal

resistance.

a) To verify Ohm’s law by using the above potential divider, the following equipments are given. An

ammeter with negligible internal resistance, a voltmeter with 10MΩ internal resistance and a 60Ω

resistor.

i) Complete the circuit using the equipments given above, and denote the positive terminals of

the ammeter and voltmeter using the symbol.

ii) A rheostat is given instead of the 5kΩ resistor. Denote the terminals of the rheostat as X, Y and

Z in the given space.

iii) Suggest a suitable value for the full scale deflection of the ammeter.

..........................................................................................................................................................

..........................................................................................................................................................

iv) What is the advantage of using an ammeter which has the full scale deflection that you

mentioned above?

..........................................................................................................................................................

..........................................................................................................................................................

v) Draw the rough sketch of the graph that you would expect from this practical.


vi) Will there be any change in the value calculated for R, if the internal resistance of the ammeter

is not zero? Explain.

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

vii) If the ammeter has internal resistance, draw the rough sketch of the graph you would expect in

the same graph, and mark it as A1.

b) If a torch bulb was used instead of the 60Ω resistor, the given graph was obtained.

i) What is the reason for the characteristics of the filament bulb to deviate from the Ohm’s

law?

..........................................................................................................................................................

..........................................................................................................................................................

ii) A torch bulb has been rated as 6V, 0.36W. When the bulb operates as rated, calculate the

resistance of the filament.

..........................................................................................................................................................

..........................................................................................................................................................

iii) If a semiconductor is used instead of a filament, draw the curve for this situation on the

same graph and mark it as A2.

Grade:- 13 (2016) - June - 2016 1 Physics - II (B)

Part - II - Essay

Answer only four questions

5)

As shown in figure (I), a 200m racing track has two straight sections and two semicircular sections. The

centre X, of a straight track is the starting and finishing point. A 4×200m relay event took place in this

track. The speed-time graph of group G, which participated in the relay, is given in figure (II). The area

MN on the track is where the baton is passed on to the next player. In the graph, 21s, 40.5s and 60.5s

denote the time when baton is transferred.





Grade :- 13 (2016) Physics - II

FWC

Fig -

Fig -


a) i) Separately find the distance that each of the first three runners ran.

ii) If the distance ran by the last runner is 202m, find the time taken to complete the 4×200m

relay race.

iii) Of these four runners, which one had the highest average speed?

iv) What is the total time taken for the first athlete to run the two semicircular portions of the

track?

v) If the maximum speeds of these athletes do not change, give two strategies that they can

follow to finish the race in minimum time.

b)

i) How does a runner obtain the force he needs to run? Copy the figure of the

runner shown here onto your answer script and denote that force on the athlete.

ii) If the mass of the first athlete is 60kg, during the first 1.5s what is the magnitude of the force

mentioned in b(i)?

iii) What is the magnitude of the angle that the athlete makes with the horizontal?

iv) When the athlete runs on a straight track, why does he run with uniform speed despite

obtaining the force mentioned in b(i)?

v) When this first athlete runs on the semicircular track, what is the centripetal force acting on

him? How does he obtain this force?

c) Figure (III) shows a section of the speed-time graph of the first athlete of the H team which takes

part in this race. At which second will this athlete catch up with the first athlete of the G team?


6) a) Endoscopes are commonly used in medicine for the purpose of viewing some internal organs. One

end of the endoscope has a small lens. The image of the internal organ formed by this lens is

conducted by total internal reflection, through the optical fibers in the endoscope, to the other end

of the endoscope. The photons in the laser light have the same energy and they all travel in parallel

to one another. As a result, Laser light is highly monochromatic and parallel. In conjunction with a

laser, the endoscope may also be used for surgery.

i) Explain how an endoscope allows a surgeon to view the stomach.

ii) What properties of laser light make it suitable to be used as a scalpel?

iii) Suggest a physical process which occurs in soft tissue exposed to laser light to enable the light

to act as a scalpel.

b) In a process known as spot welding, a pulsed laser is used to repair small tears in the retina. The

power of the laser light prior to entry into a bundle of optical fibres is 125W. 40% of the incident

power is not transmitted through the fibres.

i) Calculate the light intensity in W mm-2 of the laser beam when it is focused in to an area of

of the retina.

ii) The duration of each pulse of laser light is . Calculate the energy supplied to the retina in

one pulse.


c) The figure illustrates laser light being used to destroy unhealthy tissues.

i) Explain why one some tissue in the laser beam is destroyed.

ii) Suggest one advantage of using a lens of short focal length for the removal of a thin layer of

tissue.

7) Read the paragraph carefully and answer the questions given below.

The human heart is the pump that circulates blood throughout the body. The left ventricle of the heart

pumps blood into the aorta, which is the main artery of the human body. This blood is then distributed

among several arteries and capillaries and sent to the different parts of the body. The normal heartbeat

for a person at rest is 70 beats/minute.

The Poiseuille’s equation is often used for approximate calculations of blood flow in human body. The

flow of blood through vessels need not be a streamline flow. An empirical equation could be used to

check whether the flow is streamline or not. If the liquid of viscosity η and density ρ, flows through a

pipe of diameter D with velocity v, the Reynolds number NR will be defined as follows.

It has been verified experimentally that during streamline flow, the number NR will be less than 2000.

a) .

i) Identifying the symbols, write down the Poiseuille’s equation for the flow of viscous liquid

through a tube.

ii) State two reasons why Poiseuille’s equation is not strictly valid for the flow of blood through

arteries.

b) Suppose that a volume of 70cm3 blood is pumped into the aorta on each beat of the heart.

i) Calculate the average volume of flow rate of blood through the aorta when the person is at

rest.

ii) If the diameter of the aorta is 1cm, calculate the average speed of blood in the aorta. State any

assumptions that you have made.


c) i) Verify that the Reynolds number NR is dimensionless.

ii) Justify, showing necessary calculations, that the blood flow in part (b) is laminar. Assume that

the viscosity and density of blood at body temperature are and

respectively.

d) Now, consider the flow of blood through a horizontally situated artery with uniform cross section,

having radius 2mm. The length of the artery is 20cm. the average rate of blood flow has been

estimated to be .

i) Calculate the pressure difference between the two ends of the artery.

ii) Calculate the rate of work done by the heart in pumping blood through this artery.

8) This question is about the design of a new propulsion system for driving a boat at sea.

a)

i) Write the equation for the force acting on a moving charge placed in a magnetic field.

ii) Write the equation for the force acting on the current carrying conductor placed in a magnetic

field.

b) The first proposal – As shown in figure (I) copper bar is fixed under the boat and a large current is

passed through it. A large electromagnet produces a vertical magnetic field, as shown in the figure.

i) State the direction of the force on the bar when the current is flowing as shown in the diagram.

ii) Which law did you use in part (i)?

iii) Give two ways of increasing the force on the bar.

iv) Explain briefly whether this system will work.

c) The second proposal - As shown in figure (II), this proposal suggests passing a current through the

water instead of through the copper bar using an electrode system. Each electrode face has a

surface area of and they are apart. The drag force on the boat, which has a mass of

, is when it moves at . The current used is to be 1000A.

i) What is meant by ionization? Explain how this enables a current to flow in seawater.

ii) Explain why the boat moves when a current is passed through the seawater.

iii) What is the strength of the magnetic field required so that the thrust is sufficient to maintain a

constant speed of ?

Fig - I Fig - II


9) Answer either part (A) or part (B).

(A)

You may have seen a sign at the bottom of an electricity pylon saying “Danger. High voltage”.

Power is transmitted around the country at voltages as high as 400 000V. This has a very good

reason- to save a lot of energy.

Figure 1 suggests two ways of transmitting 25MW power from a Yorkshire power station to the

midlands.

a)

i) Power can be transmitted through the power cables at a supply voltage of 25000V.

ii) Power can be transmitted through the power cables after the voltage is stepped up to

250000V.

How much power would be wasted in heating the cables in each case, given that 200km of

cable has a resistance of 10Ω.

b) .

i) Explain why the electricity supply in your home is AC rather than DC.

ii) Use the data in figure 1 to calculate the voltage at each point X and Y.

c) The figure shows how electric power is transmitted

from generating stations to consumers on high-

voltage overhead power lines, supported by metal

pylons, which are earthed. Each conductor is

suspended vertically below the pylon structure by an

insulator which is 3.5 m long. The distribution voltage

is 380kV r.m.s. It may be assumed that the voltage

applied to each conductor has sinusoidal waveform.

Fig - I

cU II


i) Calculate the peak voltage supplied to each of the conductors.

ii) Estimate the magnitude of the maximum electric field strength between a conductor and the

pylon structure, if the field could be assumed to be uniform. (Neglect the magnetic field

induced in one conductor by another)

d) Under certain atmospheric conditions it is possible to hear sharp crackling sounds coming from the

region around the conductors.

i) State the atmospheric conditions under which the effect will become more pronounced.

Explain your answer.

ii) Suggest an explanation for this effect.

9) (B)

i) Mention how the junction field effect transistor (JFET) differs from a bipolar transistor in each of

the following factors.

i) Number of p-n junctions

ii) Charge carriers

iii) Whether the factor controlling the function is potential difference or current flow

ii)

i) Draw the output characteristic curves of an -channel junction field effect transistor.

ii) Which factor is kept constant when drawing a characteristic curve of this output?

iii) Denote the linear region, saturated region and cutoff region on your graph.

iii) Figure (I) shows a circuit used to bias an -channel

junction field effect transistor. Resistors RG and RS are

connected to the earth and resistor RD is connected

to the direct power supply VDD.

i) Reason out and explain that gate voltage VG=0.

ii) Show that drain current

.

iii) Write an equation for the drain-source voltage, VDS, in terms of VDD, ID, RD and RS.

iv) The transfer characteristics curve of this junction field effect transistor is shown in figure (II).


Consider that the biasing condition in part (b) is to be arranged such that ID=6mA. To achieve this,

the following conditions are maintained. VDD=10V, RD=500Ω and RG=1MΩ.

i) Find the value of the pinch off voltage (VGS(off)) and the maximum value of the saturated drain

current (IDS(sat)).

ii) Copy figure (II) onto your answer script and denote the operating point of this biased state as

Q.

iii) Calculate the value of RS and from that, calculate VDS.

10) Answer either part (A) or (B).

(A)

A cylinder and piston of a vehicle are shown in the diagram. The initial volume and temperature of

the system are and respectively. The area of cross section of this piston is .

Air is taken into it with a pressure of . the total weight of the cylinder and its content is

. Its specific heat capacity is . Now, heat is produced by burning the air within

the cylinder. Air, which is taken in at reaches a temperature of 177oC, pushes the piston,

and is then released from the system. Fresh air is taken into the cylinder at and the system

returns to its initial volume and pressure. This process happens 750 times per minute. From ,

the system reaches a stable state of in one minute. For the following process, the piston is

at 177oC.

Universal gas constant

The molecular mass of air

The specific heat capacity of air

i) What is the mass of air trapped in the piston each time?

ii) Find the heat gained by the air in one minute.

iii) Find the heat gained by the cylinder system in one minute.

iv) What is the rate of heat supplied to this system? (Neglect the heat loss to the environment)

v) What is the additional pressure exerted on the piston when air inside is heated from 27oC to

177oC?

vi) The piston is pushed outwards so that the pressure inside returns to . At the

constat temperature (177oC) what is the increase in volume of the gas?

vii) What is the rate of work done by the gas?

Piston

Cylinder


viii) Water at 27oC is allowed to flow around the cylinder in order to maintain its temperature

stably at 177oC. When it flows completely around the cylinder and leaves, its temperature is

87oC. What is the rate of mass flow of the water? (Assume that the cylinder continuously

gains heat as mentioned in part (c). The specific heat capacity of water is )

ix) In the appliance mentioned in part (h) (radiator) why is water allowed to flow through a long

tube that is folded many times?

x) What is the property of water that caused it to be selected in part (h)?

10) (B) Stars glow spontaneously when the nuclear energy in them is converted to other forms, such as

heat energy and light energy, due to nuclear fusion reactions. Sun is the closest star to Earth.

During the nuclear fusion reaction taking placing in the sun, four hydrogen atoms are converted

into one helium atom and two positrons (e+).

When heavy, unstable atoms are hit by neutrons moving with sufficient velocity, nuclear fission

occurs. During nuclear fusion and nuclear fission reactions a part of the mass is destroyed and

converted to energy according to the following equation. E = Δmc2. Δm is the destroyed mass,

and c is the speed of light. (c = 3×108ms-1)

a)

i) Write two differences between nuclear fusion and nuclear fission.

ii) Write the equation of nuclear reaction for the energy emitted from the sun.

iii) Calculate the amount of energy released during the nuclear fusion of hydrogen atoms. The

masses of hydrogen, helium and positron are 1.007825u, 4.002603u and 5.55×10-4u

respectively.

1u = 1.66×10-27kg = 931MeV/C2 (1eV = 1.6×10-19J)

iv) At which rate should hydrogen be consumed in order to produce energy at a rate of 1MW?

b)

i) During nuclear fission reactions, instead of protons, why are neutrons used to collide with the

atoms?

ii)

Mass of

Mass of

Mass of

Mass of

Avogadro’s number

Relative atomic mass of U

Calculate the number of neutrons released in the above reaction.

iii) Calculate the mass reduction occurring during one reaction.

iv) How much energy is produced during one reaction?

v) If 10% of the total energy released is converted to heat energy and this, in turn, is converted

into electricity with 25% efficiency, what is the mass of Uranium used in 1s to produce 300MW

of electricity?

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G.C.E. A/L Examination June - 2016 - AGARAM