Revision Pack Topic 6 – Waves - Physics...Revision Pack Topic 6 – Waves - Physics Our eyes only detect visible light and so dete ct a limited range of electromagnetic waves. Be

Revision Pack Topic 6 – Waves - Physics

Topic R/A/G Transverse and longitudinal waves Know that Waves may be either transverse or longitudinal. Understand that the ripples on a water surface are an example of a transverse wave.

Longitudinal waves show areas of compression and rarefaction. Sound waves travelling through air are longitudinal.

Describe the difference between longitudinal and transverse waves. Be able to describe evidence that, for both ripples on a water surface and sound waves in air, it is the wave and not the water or air itself that travels.

Properties of waves Be able to describe wave motion in terms of their amplitude, wavelength, frequency and period. The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position.

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.

The frequency of a wave is the number of waves passing a point each second. period = 1 / frequency {T = 1/f} period, T, in seconds, s frequency, f, in hertz, Hz

The wave speed is the speed at which the energy is transferred (or the wave moves) through the medium.

All waves obey the wave equation: wave speed = frequency × wavelength v = f λ wave speed, v, in metres per second, m/s frequency, f, in hertz, Hz wavelength, λ, in metres, m

Identify amplitude and wavelength from given diagrams Describe a method to measure the speed of sound waves in air Describe a method to measure the speed of ripples on a water surface.

Required practical activity 1: make observations to identify the suitability of apparatus to measure the frequency, wavelength and speed of waves in a ripple tank and waves in a solid and take appropriate measurements.

Electromagnetic waves – Types Electromagnetic waves are transverse waves that transfer energy from the source of the waves to an absorber.

Electromagnetic waves form a continuous spectrum and all types of electromagnetic wave travel at the same velocity through a vacuum (space) or air.

The waves that form the electromagnetic spectrum are grouped in terms of their wavelength and their frequency. Going from long to short wavelength (or from low to high frequency) the groups are: radio, microwave, infrared, visible light (red to violet), ultraviolet, X-rays and gamma rays.


Our eyes only detect visible light and so detect a limited range of electromagnetic waves.

Be able to give examples that illustrate the transfer of energy by electromagnetic waves. Properties of electromagnetic waves 1 Be able to construct ray diagrams to illustrate the refraction of a wave at the boundary between two different media.

Required practical activity 2: investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.

Properties of electromagnetic waves 2 Changes in atoms and the nuclei of atoms can result in electromagnetic waves being generated or absorbed over a wide frequency range. Gamma rays originate from changes in the nucleus of an atom.

Ultraviolet waves, X-rays and gamma rays can have hazardous effects on human body tissue. The effects depend on the type of radiation and the size of the dose. Radiation dose (in sieverts) is a measure of the risk of harm resulting from an exposure of the body to the radiation.

1000 millisieverts (mSv) = 1 sievert (Sv) You will not be required to recall the unit of radiation dose.

Be able to draw conclusions from given data about the risks and consequences of exposure to radiation.

Ultraviolet waves can cause skin to age prematurely and increase the risk of skin cancer. X-rays and gamma rays are ionising radiation that can cause the mutation of genes and cancer.

Uses and applications of electromagnetic waves Electromagnetic waves have many practical applications. For example: • radio waves – television and radio • microwaves – satellite communications, cooking food • infrared – electrical heaters, cooking food, infrared cameras • visible light – fibre optic communications • ultraviolet – energy efficient lamps, sun tanning • X-rays and gamma rays – medical imaging and treatments.

Magnetic fields The region around a magnet where a force acts on another magnet or on a magnetic material (iron, steel, cobalt and nickel) is called the magnetic field.

The force between a magnet and a magnetic material is always one of attraction. The strength of the magnetic field depends on the distance from the magnet. The field is strongest at the poles of the magnet.


The direction of the magnetic field at any point is given by the direction of the force that would act on another north pole placed at that point. The direction of a magnetic field line is from the north (seeking) pole of a magnet to the south(seeking) pole of the magnet.

A magnetic compass contains a small bar magnet. The Earth has a magnetic field. The compass needle points in the direction of the Earth’s magnetic field.

• describe how to plot the magnetic field pattern of a magnet using a compass • draw the magnetic field pattern of a bar magnet showing how strength and direction change from one point to another • explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic.

The motor effect When a current flows through a conducting wire a magnetic field is produced around the wire. The strength of the magnetic field depends on the current through the wire and the distance from the wire.

Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire. The magnetic field inside a solenoid is strong and uniform.

The magnetic field around a solenoid has a similar shape to that of a bar magnet. Adding an iron core increases the strength of the magnetic field of a solenoid. An electromagnet is a solenoid with an iron core.

• describe how the magnetic effect of a current can be demonstrated • draw the magnetic field pattern for a straight wire carrying a current and for a solenoid (showing the direction of the field) • explain how a solenoid arrangement can increase the magnetic effect of the current.

Fleming's left-hand rule (HT only) When a conductor carrying a current is placed in a magnetic field the magnet producing the field and the conductor exert a force on each other. This is called the motor effect.

Be able to show that Fleming's left-hand rule represents the relative orientation of the force, the current in the conductor and the magnetic field.

Be able to recall the factors that affect the size of the force on the conductor.

For a conductor at right angles to a magnetic field and carrying a current: force = magnetic flux density × current × length {F = B I l } force, F, in newtons, N magnetic flux density, B, in tesla, T current, I, in amperes, A (amp is acceptable for ampere) length, l, in metres, m

Electric motors (HT only)

A coil of wire carrying a current in a magnetic field tends to rotate. This is the basis of an electric motor.

be able to explain how the force on a conductor in a magnetic field causes the rotation of the coil in an electric motor





Task: Try this quiz. Answers will follow. Note – Answers will also tell you the level of difficult for each question Waves and Energy Transfer

1. Match the descriptions to the types of wave. [1 mark]

A wave which moves up and down Longitudinal

A water wave Longitudinal

A sound wave Transverse

A wave which moves forwards and backwards Transverse

2. A beam of light from a torch is shone through a glass window. Which two statements about it are correct? [1 mark]

a) The light beam travels faster through glass

b) The light beam has a shorter wavelength as it passes through glass

c) The beam of light is refracted as it passes through glass

d) The beam of light is reflected as it passes through glass 3. Using the idea of particles, describe how thermal conduction takes place in a solid. [2 marks]

4. Explain why you can see your reflection in a pond when the water is still, but not when it is choppy. [2 marks]

5. Explain what is meant by superposition of water waves. [2 marks]

6. A household uses 800 kWh of electricity at 12p per kWh, and 1000 kWh of gas at 5p per kWh. Explain what you think the total cost is. [2 marks]


7. A house is supplied with mains gas. Explain what they might use the gas for, and why scientists say no energy is lost or used up. [4 marks]

8. Michael is fitting solar panels to the roof of his house:

They weren’t cheap to buy but he tells his neighbours he expects to “have got his money back in ten years.” What does this mean? [2 marks]

9. Sue and Jo are buying a new electric kettle for their flat to make tea. They find a design they like but then find out they can buy it either with a 1000W element or a 2000W element.

Sue says “We should buy the 1000W one as it will use less electricity and be cheaper to run.” Jo says “We should buy the 2000W one as it will boil the water quicker, so energy will have less chance to escape and it will be more efficient.” The sales assistant says “Both kettles are the same shape, size and material so they will be as efficient as each other. It’s just down to how quickly you want your tea.” Who is right, and why? [4 marks]


10. Robert reads that radiation is different to conduction and convection because of the role of a medium in energy transfer. The website he is looking at says that radiation doesn’t need a medium, such as water or a metal, to work. Explain what this means. [2 marks]

11. Explain how an image is formed on the retina of the eye. Include in your account details of where refraction and absorption occur. [4 marks]

12. Explain, with reference to energy transfer and equilibrium, what will happen to a hot metal pan left to cool on a mat on a table. [4 marks]

Total ____/30


Waves and Energy Transfer Answers

1. Match the descriptions to the types of wave. [1 mark]

A wave which moves up and down Transverse

A water wave Transverse

A sound wave Longitudinal

A wave which moves forwards and backwards Longitudinal

2. A beam of light from a torch is shone through a glass window. Which two statements about it are correct? [1 mark] b), c) Difficulty level: difficult Skill level: application

3. Using the idea of particles, describe how thermal conduction takes place in a solid. [2 marks] (the answer should contain two of the following) 1) The hotter the object the faster the particles vibrate 2) Energy is transferred as the particles collide 3) Thermal equilibrium is reached when all the particles vibrate at the same speed Difficulty level: moderate Skill level: knowledge 4. Explain why you can see your reflection in a pond when the water is still, but not when it is choppy. [2 marks] (the answer should contain the following) 1) Choppy water produces diffuse scattering (reflects light in different directions) 2) A smooth water surface produces specular reflection (reflects light in the same direction) Difficulty level: difficult Skill level: application 5. Explain what is meant by superposition of water waves. [2 marks] (the answer should contain the following) 1) When crests or troughs coincide, waves add together to make a bigger wave 2) When crests coincide with troughs, waves cancel each other out Difficulty level: difficult Skill level: knowledge 6. A household uses 800 kWh of electricity at 12p per kWh, and 1000 kWh of gas at 5p per kWh. Explain what you think the total cost is. [2 marks] (the answer should contain the following) (1) 800 multiplied by 12 equals 9600p equals £96; 1000 multiplied by 5 equals 5000p equals £50 (3) Total equals £146 (or correct addition of their figures) (4) Any other relevant point Difficulty level: moderate Skill level: knowledge 7. A house is supplied with mains gas. Explain what they might use the gas for, and why scientists say no energy is lost or used up. [4 marks] (the answer should contain four of the following)


1) Gas used for heating and/or cooking 2) Energy transferred to the surroundings 3) Quantity of energy stored in the gas is the same as the energy now stored in the surroundings 4) Total amount of energy remains the same 5) Law of Conservation of Energy Difficulty level: difficult Skill level: application 8. Michael is fitting solar panels to the roof of his house:

They weren’t cheap to buy but he tells his neighbours he expects to “have got his money back in ten years.” What does this mean? [2 marks] (the answer should contain the following) 1) Cheaper way of producing electricity than buying it from an electricity supply company 2) After ten years the savings will have covered the cost of installation Difficulty level: difficult Skill level: evaluation 9. Sue and Jo are buying a new electric kettle for their flat to make tea. They find a design they like but then find out they can buy it either with a 1000W element or a 2000W element.

Sue says “We should buy the 1000W one as it will use less electricity and be cheaper to run.” Jo says “We should buy the 2000W one as it will boil the water quicker, so energy will have less chance to escape and it will be more efficient.” The sales assistant says “Both kettles are the same shape, size and material so they will be as efficient as each other. It’s just down to how quickly you want your tea.” Who is right, and why? [4 marks] (the answer should contain four of the following) 1) The 1000W kettle will take longer to get a certain amount of water to boiling point. 2) It takes a certain amount of energy to get the water to boil 3) The 2000W kettle will supply the energy more quickly


4) The quicker the energy is supplied, the less chance it has to escape 5) The 1000W kettle won’t be cheaper to run – more energy will have escaped to the surroundings as it takes longer to boil the water 6) They won’t be as efficient as each other – taking longer to heat the water means more energy lost. Difficulty level: moderate Skill level: evaluation 10. Robert reads that radiation is different to conduction and convection because of the role of a medium in energy transfer. The website he is looking at says that radiation doesn’t need a medium, such as water or a metal, to work. Explain what this means. [2 marks] (the answer should contain the following) 1) Conduction and convection only take place if there is a medium for energy to be transferred through 2) Radiation needs no medium and energy is transferred better in the absence of a medium. Difficulty level: difficult Skill level: evaluation 11. Explain how an image is formed on the retina of the eye. Include in your account details of where refraction and absorption occur. [4 marks] (the answer should contain four of the following) 1) Rays enter through the cornea, pass through the lens and land on the retina 2) Refracted at cornea 3) Refracted at lens 4) Absorbed at retina 6) Any other relevant point Difficulty level: difficult Skill level: knowledge 12. Explain, with reference to energy transfer and equilibrium, what will happen to a hot metal pan left to cool on a mat on a table. [4 marks] (the answer should contain four of the following) 1) Cool down by conduction through mat 2) Cool down by convection through air 3) Cool down through radiation 4) Will reach equilibrium 5) It’s temperature will remain steady 6) Any other relevant point Difficulty level: difficult Skill level: application


Task: Data and calculation questions for waves.

1. Draw on the wavelength and the amplitude of the following waves. (4)

2. Calculate the time period and the frequency of each wave. (4) 3. A wave travelling at 3000 m/s has a wavelength of 1 m.

a. Calculate the frequency of the wave. b. Calculate the time period of the wave. c. How many complete wave cycles will occur in:

i. 1 second? ii. 10 seconds?

iii. 1 minute? (5) 4. A radio wave has a wavelength of 1000 m and a frequency of 3x105 Hz.

Calculate the wave speed. (1)

6 Seconds

6 Seconds


5. A gamma wave has a wavelength of 1x10-12 m and a frequency of 3x1020 Hz. Calculate the wave speed. (1)

Mark scheme:

1. Wavelengths correctly drawn for both (2) or for one (1)

Amplitudes correctly drawn for both (2) or for one (1) 2. First wave: time period = 6 s/2 = 3 s (1)

Frequency = 1/3 s = 0.3 Hz (1) Second wave: time period = 6 s/6 = 1 s (1) Frequency = 1/1 s = 1 Hz (1)

3. A wave travelling at 3000 m/s has a wavelength of 1 m.

a. f = v/ = 3000/1 = 3000 Hz. (1) b. T = 1/f = 1/3000 = 3.3x10‐4 s (1)

c. How many complete wave cycles will occur in:

i. 1/3.3x10‐4 s = 3000 wave cycles. (1)

ii. 10/3.3x10‐4 s = 30000 wave cycles. (1)

iii. 60/3.3x10‐4 s = 180 000 wave cycles. (1)

4. v = f = 1000 x 3x105 = 3x108 m/s (1)

5. v = f = 1x10‐12 x 3x1020 = 3x108 m/v (1)

Total Marks: 15


Task: Give yourself 30 minutes and try these exam-style questions. Q1. The table gives the frequencies of sound that different animals can hear.

Animal Lowest frequency it can hear in Hz

Highest frequency it can hear in Hz

Human 64 23 000

Dog 67 45 000

Mouse 1 000 91 000

Rat 200 76 000

Cat 45 64 000

Tuna 50 1 100

Canary 250 8 000

Chicken 125 2 000

(a) (i) Which animal can hear the lowest sound frequency?

................................................................................................................... (1)

(ii) Which animal can hear the smallest range of frequencies?

................................................................................................................... (1)

(b) (i) What is the name given to sound frequencies higher than those that humans can hear?

................................................................................................................... (1)


(ii) Give one industrial use of this type of sound.

................................................................................................................... (1)

(Total 4 marks)

Q2. The diagram shows a water wave drawn to scale.

(a) What is the wavelength of this water wave? ............................... cm (1)


(b) What is the amplitude? ............................... cm (1)

(c) Twelve waves pass an observer in four seconds.

What is the frequency of the waves? Show clearly how you work out your answer and give the unit.

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

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

Frequency = ..................................................................... (3)

(Total 5 marks)

Q3. (a) The diagram represents the electromagnetic spectrum. Four of the waves have not been named. Draw lines to join each of the waves to its correct position in the electromagnetic spectrum. One has been done for you.

(2)

(b) Complete the following sentence by choosing the correct answer and crossing out in


the box the two lines which are wrong.

The speed of radio waves through a vacuum is the speed of

light through a vacuum. (1)

(d) The diagram shows an X-ray photograph of a broken leg.

Bones show up white on the photographic film. Explain why.

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

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

............................................................................................................................. (2)

(Total 5 marks)

Q4.Waves may be longitudinal or transverse.

(a) Describe the differences between longitudinal waves and transverse waves.

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

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

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

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

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


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

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

......................................................................................................................... (3)

(b) Radio waves are electromagnetic waves.

Describe how radio waves are different from sound waves.

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

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

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

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

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

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

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

......................................................................................................................... (4)

(Total 7 marks)

Q5.A note was played on an electric keyboard.

The frequency of the note was 440 Hz.

(a) (i) What does a frequency of 440 Hz mean?

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

............................................................................................................... (1)

(ii) The sound waves produced by the keyboard travel at a speed of 340 m / s.


Calculate the wavelength of the note.

Give your answer to three significant figures.

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

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

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

Wavelength = ........................................ metres (3)

(b) Figure 1 shows a microphone connected to a cathode ray oscilloscope (CRO) being used to detect the note produced by the keyboard.

Figure 1

Figure 2 shows the trace produced by the sound wave on the CRO.

Figure 2

A second note, of different wavelength, was played on the keyboard.


Figure 3 shows the trace produced by the sound wave of the second note on the CRO.

Figure 3

The settings on the CRO were unchanged.

What two conclusions should be made about the second sound wave produced by the keyboard compared with the first sound wave?

Give a reason for each conclusion.

Conclusion 1 ..................................................................................................

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

Reason ..........................................................................................................

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

Conclusion 2 ..................................................................................................

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

Reason ..........................................................................................................

........................................................................................................................ (4)

(Total 8 marks)


M1. (a) (i) cat 1

(ii) tuna 1

(b) (i) ultrasound

allow ultrasonic 1

(ii) cleaning / quality control / flaw detection / medical scanning / animal scaring / sonar

1 [4]

M2. (a) 4 1

(b) 3 1

(c) 3

correct answer with no working = 2 allow 1 mark for f = number ÷ time or correct working i.e., 12 ÷ 4 N.B. correct answer from incorrectly recalled relationship / substitution = 0

2

Hz / hertz

accept HZ, hz, hZ allow waves / cycles per second allow wps, w/s, cps, c/s

1


[5]

M3. (a) all three correct

one only correct, 1 mark only

allow names in boxes

there should be only one line from or to each box 2

(b) the same as 1

(d) any two from:

• bones absorb X-rays

• so film not exposed

• X-rays pass through flesh or skin or

• body or tissue (to expose film)

allow X-rays cannot pass through bones 2

[5]


M4.(a) the oscillation / vibration (causing the wave)

a movement causes the wave is insufficient 1

for a transverse wave is perpendicular to the direction of energy transfer

accept direction of wave travel 1

and for a longitudinal wave is parallel to the direction of energy transfer

accept direction of wave travel

if no marks awarded allow 1 mark for correctly linking perpendicular with transverse and parallel with longitudinal

the marks may be scored by the drawing of two correctly labelled diagrams

1

(b) for radio waves:

accept converse for each mark

are transverse 1

travel at speed of light / higher speed 1

have greater frequencies 1

can travel through vacuum

accept sound waves are not electromagnetic for 1 mark 1


[7]

(a) (i) 440 (sound) waves produced in one second

accept vibrations / oscillations for waves 1

(ii) 0.773 (metres)

allow 2 marks for an answer that rounds to 0.773

allow 2 marks for an answer of

allow 2 marks for an answer of 0.772

allow 1 mark for correct substitution ie 340 = 440 × λ 3

(b) (sound is) louder

do not accept the converse 1

as amplitude is larger

waves are taller is insufficient 1

higher pitch / frequency 1

as more waves are seen

reference to wavelengths alone is insufficient

waves are closer together is insufficient 1

[8]


Stage 2: 32 minutes to try these exam-style questions. Q1.Waves may be longitudinal or transverse.

(a) Describe the differences between longitudinal waves and transverse waves.

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

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

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

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

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

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

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

......................................................................................................................... (3)

(b) Radio waves are electromagnetic waves.

Describe how radio waves are different from sound waves.

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

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

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

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

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

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

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

......................................................................................................................... (4)

(Total 7 marks)


Q2.A note was played on an electric keyboard.

The frequency of the note was 440 Hz.

(a) (i) What does a frequency of 440 Hz mean?

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

............................................................................................................... (1)

(ii) The sound waves produced by the keyboard travel at a speed of 340 m / s.

Calculate the wavelength of the note.

Give your answer to three significant figures.

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

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

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

Wavelength = ........................................ metres (3)

(b) Figure 1 shows a microphone connected to a cathode ray oscilloscope (CRO) being used to detect the note produced by the keyboard.

Figure 1


Figure 2 shows the trace produced by the sound wave on the CRO.

Figure 2

A second note, of different wavelength, was played on the keyboard.

Figure 3 shows the trace produced by the sound wave of the second note on the CRO.

Figure 3

The settings on the CRO were unchanged.

What two conclusions should be made about the second sound wave produced by the keyboard compared with the first sound wave?

Give a reason for each conclusion.


Conclusion 1 ..................................................................................................

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

Reason ..........................................................................................................

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

Conclusion 2 ..................................................................................................

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

Reason ..........................................................................................................

........................................................................................................................ (4)

(Total 8 marks)

Q3. Radio waves, ultra-violet, visible light and X-rays are all types of electromagnetic radiation.

(a) Choose wavelengths from the list below to complete the table.

3 × 10–8 m 1 × 10–11 m 5 × 10–7 m 1500 m

TYPE OF RADIATION

WAVELENGTH (m)

Radio waves

Ultra-violet

Visible light

X-rays

(4)

(b) Microwaves are another type of electromagnetic radiation.

Calculate the frequency of microwaves of wavelength 3 cm. (The velocity of electromagnetic waves is 3 × 108 m/s.)


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

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

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

............................................................................................................................. (4)

(Total 8 marks)

Q4. (a) Microwaves and visible light are two types of electromagnetic wave. Both can be used for communications.

(i) Give two properties that are common to both visible light and microwaves.

1 ............................................................................................................

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

2 ............................................................................................................

............................................................................................................... (2)

(ii) Name two more types of electromagnetic wave that can be used for communications.

................................................... and .................................................. (1)

(b) Wi-Fi is a system that joins computers to the internet without using wires. Microwaves, with a wavelength of 12.5 cm, are used to link a computer to a device called a router. Microwaves travel through the air at 300 000 000 m/s.

Calculate the frequency of the microwaves used to link the computer to the router.


Show clearly how you work out your answer and give the unit.

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

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

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

Frequency = .............................................................. (3)

(c) Wi-Fi is used widely in schools. However, not everyone thinks that this is a good idea.

A politician commented on the increasing use of WiFi. He said: ‘I believe that these systems may be harmful to children.’

However, one group of scientists said that there is no reason why Wi-Fi should not be used in schools. These scientists also suggested that there is a need for further research.

(i) Suggest what the politician could have done to persuade people that what he said was not just an opinion.

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

............................................................................................................... (1)

(ii) Why did the group of scientists suggest that there is a need for further research?

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

............................................................................................................... (1)

(Total 8 marks)


M1.(a) the oscillation / vibration (causing the wave)

a movement causes the wave is insufficient 1

for a transverse wave is perpendicular to the direction of energy transfer

accept direction of wave travel 1

and for a longitudinal wave is parallel to the direction of energy transfer

accept direction of wave travel

if no marks awarded allow 1 mark for correctly linking perpendicular with transverse and parallel with longitudinal

the marks may be scored by the drawing of two correctly labelled diagrams

1

(b) for radio waves:

accept converse for each mark

are transverse 1

travel at speed of light / higher speed 1

have greater frequencies 1

can travel through vacuum

accept sound waves are not electromagnetic for 1 mark 1

[7]


(a) (i) 440 (sound) waves produced in one second

accept vibrations / oscillations for waves 1

(ii) 0.773 (metres)

allow 2 marks for an answer that rounds to 0.773

allow 2 marks for an answer of

allow 2 marks for an answer of 0.772

allow 1 mark for correct substitution ie 340 = 440 × λ 3

(b) (sound is) louder

do not accept the converse 1

as amplitude is larger

waves are taller is insufficient 1

higher pitch / frequency 1

as more waves are seen

reference to wavelengths alone is insufficient

waves are closer together is insufficient 1

[8]

M3. (a) radio – 1500 ultra violet 3 × 10–8

visible – 5 × 10–7


X-rays – 1 × 10–11

4

(b) 1 × 1010Hz 1010HzOK

for 4 marks

else 1 × 1010

for 3 marks

else 3 × 108/0.03

for 2 marks

else v = frequency × wavelength or 3 × 108 = 0.03f any answer with unit Hz scores 1, 2 or 3

for 1 mark 4

[8]

M4. (a) (i) any two from:

• travel at the same speed (through a vacuum)

accept travel at the speed of light

accept air for vacuum

• can travel through a vacuum / space

do not accept air for vacuum

• transfer energy

• can be reflected

• can be refracted

• can be diffracted

• can be absorbed


• can be transmitted

• transverse

accept any other property common to electromagnetic waves

accept travel at the same speed through a vacuum for both marks

do not accept both radiated from the Sun 2

(ii) infra red

both required for the mark

radio(waves)

accept IR for infra red 1

(b) 2 400 000 000

correct transformation and substitution gains 1 mark

ie or

an answer of 24 000 000 gains 1 mark

either 2 400 000 kHz

or 2 400 MHz scores 3 marks but the symbol only scores the 3rd mark if it is correct in every detail

2

hertz

accept Hz

do not accept hz 1

(c) (i) presented (scientific) evidence / data

do an experiment / investigation is insufficient 1


(ii) to find out if there is a hazard (or not)

accept to find out if it is safe

accept not enough evidence to make a decision

not enough evidence is insufficient 1

[8]

Magnetic field – 7 minutes

. A student investigates the electromagnetic force acting on a wire which carries an electric current. The wire is in a magnetic field.

The diagram shows the circuit which the student uses.

(a) Draw an X on the diagram, with the centre of the X in the most strongest part of the magnetic field.

(1)

(b) Give one change that she can make to the magnets to decrease the electromagnetic force on the wire.

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

........................................................................................................................ (1)


(c) The student wants to change the electromagnetic force on the wire without changing the magnets or moving their position.

(i) Give one way in which she can increase the electromagnetic force.

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

............................................................................................................... (1)

(ii) Give one way in which she can reverse the direction of the electromagnetic force.

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

............................................................................................................... (1)

(Total 4 marks)


Q2. (a) A laboratory technician sets up a demonstration.

A flexible wire is suspended between the ends of a horseshoe magnet. The flexible wire hangs from a cotton thread. When the switch is closed, the wire kicks forward.

Identify the effect which is being demonstrated.

........................................................................................................................ (1)

(b) A teacher makes some changes to the set-up of the demonstration.

What effect, if any, will each of the following changes have?

(i) more powerful horseshoe magnet is used.

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

............................................................................................................... (1)

(ii) The connections to the power supply are reversed.

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

............................................................................................................... (1)

(Total 3 marks)


M1. (a) centre of the X midway between the poles

intention correct as judged by eyeexample

1

(b) move the poles further apart

accept turn for move

accept ends / magnets for poles

accept use weaker magnets

do not accept use smaller magnets 1

(c) (i) add more cells (to the battery)

do not accept ‘use a bigger battery’

accept increase the potential difference / voltage

accept increase the current

orreduce the resistance (of the variable resistor)

do not accept any changes to the magnets, to the wire or to their relative positions

1

(ii) reverse (the polarity of) the battery

accept turn the battery / cells round

accept swap the connections to the battery

do not accept any changes to the magnets, to the wire or to their relative positions

1 [4]


M2. (a) motor (effect) 1

(b) (i) wire kicks further (forward)

accept moves for kicks

accept moves more

accept ‘force (on the wire) increased’ 1

(ii) wire kicks back(wards) / into (the space in) the (horseshoe) magnet

accept moves for kicks

accept ‘direction of force reversed’ 1

[3]

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Revision Pack Topic 6 – Waves - Physics...Revision Pack Topic 6 – Waves - Physics Our eyes only detect visible light and so dete ct a limited range of electromagnetic waves. Be