IES Paper 1 Soln

1

ESE 2015 Examination-13th

Morning (E&T-1 PAPER-SET-B)

1. (A) r

r l

R0.89159

R R

But

2 2

2 2

r

dl 1R 80 80 12.3

8

So Rl=1.5 ohm

Reference: Same Qs has been done in EMT Class Notes Page No. 250 as shown below:

2. (B) Both Near and Far field will be equal at distance x= /2= /6

Here =8

6

3 10300m

10

so x=50m

Reference: Same Formula has been done in EMT Class Notes Page No. 237

3. (D)

Systematic error: These are the errors associated with a flow in equipment or in design of experiment

which can be estimated by repeating experiments with some equipment.

Random error: In experimental measurement these are caused by unknown changes in experiment this

change may occur in measuring instruments or in environmental conditions.

Loading errors: These errors result from the influence exerted by act of measurement on physical device

being tested. It is the basic that measuring process inevitable alters the characteristic of both the source of

measured quantity and measuring system itself.

Reference: Definitions in E&I Class Notes Page No. 6&14

4. (C)

Range of error = Avg value extreme end value 110.06 110.11 .0.05 Range of error = Avg value extreme end value 110.06 110.02 .0.04

0.05 0.04Average Rangeof error 0.045

2

Reference: Same Q in ESE-2015 Test series Q.59 in Topic Test of Measurement & Material

5. (D)

2

2P I R dP dI dR

100% 2 100% 100%P I R

25mA 2% 25

10mA 2% 5%10

So dP

100% 2 5% 10%P = 20%

Reference: Same type of Q in E&I Class Notes Page No. 12

6. (A)

7. (D) In case of Moving coil instrument there are all three torques at coil

1. Control torque

2. Deflecting torque

3. Damping torque

Reference: Same topics discussed in E&I Class Notes Page No. 40

8. (A) 6

6

R / R 6 10K 3

l / l 2 10

Reference: Refer E&I class notes strain gauge

9. (B)

Value of power delivered to load will be Maximum in case (B) Only. Option(C) is not the answer because

Here source is variable not load and in this case current value is not maximum.

Reference: Same question was asked in GATE Full Mock test series.

10. (D)

1 count error in digital frequency meter is Q error and this ambiguity can exist in least Significant Digit which is often referred as Q error. This ambiguity can be due to non coherence between internal clock

frequency and input signal.

11. (C)

Input voltage to be measured is applied to heating element and heating effect of thermocouple is sensed by

thermocouple attached to heater. This heating power is proportional to square of RMS value of input RMS

value But Thermocouple is non linear which can be reduced by use of two thermocouples one is measuring

and other one is balancing thermocouple .

12.(C)

In DArsonaval Galvanometer movement is caused by electromagnetic deflection using a coil of wire and magnetized field. When current is passed a needle is deflected. whenever es flow through a conductor

3

magnetic field proportional to current is produced .This effect is useful for measuring current and is

employed in many practical meter. Most of the meters in used has DArsonaval movement because of magnetic effect.

Reference: Same Q was discussed in doubt classes of E&I under topic conversion of Galvanometer

13.(B)

Active device is one which emits its own radiation and device which modulates the incident radiation to

provide necessary display is known as passive device. Exmaple of active display devices are CRT and LED

LCD is main example of passive device.

Reference: Same concept was discussed in doubt classes of E&I under topic LED and LCD

14. (D)

A CRT operating with high frequency signal is required to provide a display of adequate brightness for a

rapidly changing waveform. This is also called 4th

anode and brighter display is obtained

Reference: Same concept was discussed in doubt classes of E&I under topic post deflection in CRO

15. (D)

Peak-peak amplitude = 6 cm Peak amplitude=3 cm

Value of voltage =5V

3cm 15cm

RMS value=15V

10.6V2

Reference: Simple and direct Q many such type of Qs are done in class based upon unit

16. (C)

Reference: Direct concept from Digital Electronics class notes page no.201

17. (B)

18. (C)

A Pick up device is a transducer that captures mechanical vibration and converts it to an electrical signal that

is amplified recorder or broadcast. LVDT converts linear displacement only and not angular displacement

Reference: Direct Qs from previous year paper which was given in Full Mock test also.

4

19.(C)

Magnetic tape consists of narrow plastic ribbon coated with fine particles of iron oxide or other readily

magnetizable material. In recoding on tape an electrical signal is passed through a recording head as tape is

drawn past leaving a magnetic imprint on tapes surface.

20.(B) F

YA

5

2

2 10 N 100 N

mm / mm

550 10

But

R/RK

/

5R

3 50 10R

5 2150 10 0.15 10

So R

0.15%R

Reference: Asked in previous year IES exams same question is in assignment

21.(A)

Radius of nth

Bohr orbit

2

n H

nr r

ze

2

n

2r 0.529

2 1.058A

22.(A) Metal has Hall coefficient near to zero while Intrinsic S.C has negative value.

Reference: Same Qs has been done in EDC Class Notes Page No. 52 as shown below

23. (B)

917 10 met

22cm 2 10 met

6 2A 5 10 m

9 2 2

6 2

17 10 2 10 metR

A 5 10 m

56.8 10 68 ohm

Reference: Asked in previous year IES exams same question is in assignment and done in class

5

24. (B) Conductivity of semiconductor can be increased by doping the material with some impurity.

Reference: Simple and direct Q many such type of Qs are done in class.

25. (D) Insulator has high value of Energy gap which is generally greater than 3 eV

Reference: Same Concept has been done in EDC Class Notes Page No. 1 as shown below

26. (B)

Reference: Same Concept has been done in EDC Class Notes Page No. 8 as shown below

27.(A)

Reference: Same Concept has been done in EDC Class Notes Page No. 8 as shown above

28. (B) pn

n p

DD KT

q

Reference: Same Concept has been done in EDC Class Notes Page No. 39 as shown above

29.(B)

When no external voltage is applied between terminals of PIN diode the concentration gradient across the

function cause diffusion of carriers. The width of depletion region in I layer is relatively large. Now if a

reverse bias voltage is applied and increases gradually the depletion region becomes thicker. A swept out

voltage ( a particular value of reverse bias) all the free carriers are swept out of intrinsic layer. with further

increase of reverse bias the depletion region widens in highly doped semiconductor regions with further

increase in reverse bias the depletion region widens in highly doped semiconductor regions. When PIN

diodes are used as microwave switch and when they are biased in OFF condition the bias is usually beyond

the swept out voltage (usually 2 volt)

Reference: Same Concept has been done in Microwave Class Notes in PIN diode

30. (A) statement 1 is wrong because there is no voltage change but voltage is produced.

Reference: Same Concept has been done in material class notes as shown above

6

31.(A)

11z R R 2R

12 21

2R Rz z R z

R 2R

222z 2R z 3R

211222

z R 1h2z 2R

Reference: exactly same Q was done in network theory Class Notes Page No. 121 as shown below

32. (B) 1

st band Yellow 4

2nd

band Violet 7

3rd

band Red Multiply by 100

4th

band Silver Tolerance = 10%

So Resistance Value is 4700 10% 4.7k 10%

33. (A)

Manganin has very high temperature stability and i.e. why this is used for heating elements.

Reference: exactly same line was told in material science class Notes as shown below

34. (C)

ADR 10 10 10 30

7

Reference: Simple and direct Q many such type of Qs are done in class.

35. (D) It is a wheat stone budge.

ABR 15 ||15 15/2

Reference: Much wheat stone bridge based Qs are done in class notes of network Page no.13-15

36. (D) eqC 3 3|| 6 3 2 5 F

Reference: Simple Q

37. (D) complex3

P 272

2rmsI R 3/2

So here R 3

X 4

So correct answers are (A) or (D)

m

5 5I

R j L R jL

2

rms 2 2

25 1 3P I R R

2 2R L

2 2

R 3

R L 25

&

2 2

L 4

R L 25

R 3

L 4

2 2

3/4L 3

9 25L L

10

3 /4L 16

25

2

3

L 25

L 4 R 3

Reference: Simple and direct Q many such type of Qs are done in class

38. (C)

Reference: Same Q was done in class notes of material as shown below

8

39. (D) 10 3

in 1.5 10 /cm 17 3

dn N 10 /cm

20

2

i 17

2.25 10n.p n p

10

So 3 3p 2.25 10 /cm

Reference: Exact Q.78 in Assignment of EDC chapter-1

40.(D) Tunnel diode is used at microwave frequencies and it is basically a negative resistance amplifier and

oscillator.

Reference: Tunnel diode is discussed in detail in microwave

41. (B)

Numbers of independent meshes are equal to number of links and numbers of independent nodes are equal

to number of twigs.

42. (B)

11 223 5

z z 42

12 215 3

z z 12


9

43. (C)

11 22 12 21z z z z Which is not accepted?


44. (B) Y s 1 s

1

z s1 s

1

Y s 1 1 s1


45. (A) In Equipotential surface Electric field is always normal to surface.

Reference: All points asked in Qs were discussed in EMT class notes page no. 43 as shown below.

10

46. (B) 1 22

0

q q1F

4 x

Let 1 2q q Q & 2 1q Q q

1 1

2

0

q Q q1F

4 x

11

dF0 Q 2q 0

dq

1

QSo q

2

Reference: exactly same Q was asked in GATE-2015 Topic test series Q.13

47.(A) 0 1 22I I

F/4 d

710 2 1000 1500

0.1

= 5 7 130 10 10 10 = 3N

Reference: Same formula and many Qs on that formula were discussed in EMT class notes on page no. 77

as shown below.

48.(A) 3

2

1 1

20 10I 400A I 20A

50

3

2 2

20 10I 100A I 10A

200

11


49. (B) Ammeter means high resistance in series and voltmeter means low resistance in parallel.

50.(C)

1 y xE K a a

2 y xE K a a

3 y xE K a a

Here 1 2 1 3E E 0 and E E 0

x y z

1 3

a a a

E E 1 1 0

1 1 0

za 1 1 0

Reference: Many similar Qs are done in EMT class notes from page no 21-22

51.(B) Field at P due to q1 is x

1 2

0

a2E

4 2

Field at P due to q2 is y

2 2

0

a1E

4 1

x yE k 0.5a a

so tan 2

Reference: Many similar Qs are done in EMT class notes from page no 21-23

52. (C) 9 p100

E cos 10 t 6z u V/m

D 0 rdE

Jdt

9 9 20 p1 100

10 sin (10 6z) u A/m

9 2

p

1 100sin (10 t 6z) u A/m

36

9 2

p

0.9sin (10 t 6z) u A/m

Reference: Formula and concept has discussed at page no.108 as shown below

53. (B)Both Electric and Magnetic field are perpendicular to each other and not parallel to each other so

statement 2 is wrong.

Reference: Same was discussed in EMT class notes on page no. 117 as shown below.

12

54. (D)

Transverse nature of Electromagnetic waves in an electromagnetic wave, the electric and magnetic field

vectors oscillate perpendicular to the direction of propagation of electromagnetic wave. This shows that the

electromagnetic waves are transverse in character. Polarization represents time varying behavior of field

Reference: Same was discussed in EMT class notes on page no. 117 as shown above.

55. (A)

Reference: Same concept was discussed in EDC class notes on page no. 92 as shown below

56.(A) 0z 50 & Rz 750

50 750

K K 150 750

So VSWR

Reference: exact question was discussed in EMT class notes on page no. 169 as shown below

57. (B)

13

A viscosity meter is an instrument used to measure the viscosity of a fluid. Viscometers only measure under

one flow condition. In general either the fluid remains stationary and an object moves through it, or the

object is stationary and the fluid moves past it. The drag caused by relative motion of the fluid and a surface

is a measure of the viscosity. This drag force is also known as frictional force and this force exerted on

spherical objects with very small Reynolds numbers.

58. (B)

Reference: exact concept was discussed in EMT class notes on page no. 199 as shown below

59.(A) 2

1 2

Pt GtP w/m

4 (4)

is cross sectional area

2

2 2 6

212

r e2 2

Pt Gt (2.4) mP watt

4 (4) 10

Pt Gt (2.4) m 1P A 10

4 (4) (5)

But r e24

G A

212 2

r r2 2 2

212 2

r r2

Pt Gt (2.4)P 10 G

(4 ) (4) (5)

Pt Gt (2.4)P 10 (0.06) G

(4 ) 16 25

60. (D)

Since the operating principles of low-frequency and microwave antennas are essentially the same, the

electrical characteristics are also very similar. You will need a fundamental knowledge of radar and

communications antenna electrical theory in your shipboard antenna maintenance work. Antenna theory is

primarily a design consideration of antenna size and shape requirements that depend on the frequency used.

A brief description of antenna electrical characteristics is sufficient for the needs of most students of

electronics. Reference: http://www.tpub.com/neets/book11/46.htm

61. (C)

Smaller is reverse recovery time lesser will be time for removal of storage charge hence is used for fast

switch. So it is used for high frequency applications. Reverse recovery time is as shown in figure.

14

Reference: Concept of reverse recovery time was discussed in EDC class notes on page no. 103 as shown

below

62. (C)

Reference: Exactly same line was discussed in EDC class notes on page no. 268 as shown below

63. (B)

Reference: Exactly same question was discussed in EDC class notes on page no. 275 as shown below

64. (D)

Since one junction is forward biased and other is reverse biased so depletion layer will be different less for

forward biased and large for reverse biased.

Reference: very simple concept and many such type of Qs are done in class

65. (A)

A Free Wheel Diode (FWD) at the output of a full wave rectifier will improve the input PF in an SCR phase

controlled converter due to ending the input current waveform earlier by permitting internal free-wheeling.

66. (C)

Reference: Exactly same line was discussed in EDC class notes on page no. 337 as shown below

15

67. (C)

68. (C)

The property of a magnetic circuit of opposing the passage of magnetic flux lines, equal to the ratio of the

magneto motive force to the magnetic flux. Reluctance is the opposition that a ferromagnetic material shows

to establishment of magnetic field.It is analogous to resistance in a circuit.

Ferromagnetic materials are the material which when placed in magnetic field shows strong magnetization

in direction of magnetic field.

Reference: Exactly same line was discussed in material science classes under definition of reluctance.

69.(B)

Reference: Exactly same line was discussed in Analog classes notes on page no.197

70.(B)

Reference: Exactly same line was discussed in Analog classes notes on page no.98. in Darlington pair

71. (D)

Reference: Exactly same question was discussed in EDC classes notes on page no.314. as shown below

16

72. (D)

Reference: Exactly same question was discussed in Digital classes notes on page no.251. as shown below

73.(B)

An optocoupler (or an optoelectronic coupler) is basically an interface between two circuits which operate at

(usually) different voltage levels. The key advantage of an optocoupler is the electrical isolation between the

input and output circuits. With an optocoupler, the only contact between the input and the output is a beam

of light. Because of this it is possible to have an insulation resistance between the two circuits in the

thousands of megohms. Isolation like this is useful in high voltage applications where the potentials of two

circuits may differ by several thousand volts.Statement-3 is wrong and cant be used for joint. 74.(A) Reference: Exactly same question form Professor P.J.Paul Book shown below.

17

75. (A) (A) h[0] 0 for n 0 , so it is caused system

For stable system

n

n 0 n 0

1h[n] 2

2

Hence stable system

Reference: Direct and simple Q many such type of Qs were discussed.

76. (A)

Reference: Exactly same line was discussed in Network class notes on page no. 192 as shown below

77.(B) 00

21

N

So 0(N 2 ) which is not a rational number hence non-periodic

Reference: Exactly same line was discussed in Signal class notes on page no. 22 as shown below

18

78. (C)

Ideal Low pass filter is not physically realizable because for LPF impulse response exists for n

19

1

1

1

1

1

Constantan 35 v k

Nickel 25 v k

Copper 6 v k

Iron 18.5 v k

Nichrome 25 v k

Here metal A is platinum:

AB AC BC AC AB BCB C E E E E E E

Nichrome costantan 25 35 60 60

Nickel costantan 25 35 10 10

Copper Nickel 6 25 31 31

Platinum costantan 0 35 0 0

85.(C)

Reference: exactly same line was discussed in case-3 in network theory notes as shown below on page-92

86.(A)

Reference: exactly same line was discussed in superconductor as shown below.

87. (A)

Reference: EDC class notes Page-212

20

88. (B)

Pervoskite group material goes from tetragonal to monoclinic structure below Curie temperature it means it

goes from symmetric to asymmetric nature. Both statements are correct but explanation is not correct.

89.(D)It should be greater than Threshold Voltage and not less than.

Reference: EDC class notes Enhancement working

90. (B)

Reference: EDC class notes MOSFET working

91. (A)

Reference: Direct Question based upon this book theory.

92. (B)

Reference: energy signal in signal system class notes page-5

93.(A)

94. (B) Reference: signal system class notes page-105

21

95. (A)

Ferrite cored inductors are made of high resistivity materials so they have low loss at high frequency and

quality factor is inversely proportional to R so Q value will be high. Due to low loss or high Q factor only

Ferrite cores are used in high frequency tuned circuit.

96.(A) 2

2 2

Ir IrFor r R H while I(r)

2 R R

if r increases current increases with r

2 while dl or circumference

increases with r

Reference: Based upon concept given on page-70 in EMT class notes given below

97.(C)

H H

BI BIV R

n.e.t t Here B is magnetic flux density

Hall Effect can sense carrier concentration so statement-II is wrong.

Reference: Concept and Formula in EDC class notes on Page No. 52

98. (A)

99.(D) 2P I R

dR dP 2dI1.5 2 1 3.5

R P I

Reference: Same type of Q in E&I Class Notes Page No. 12

22

100. (B)

Actually when we employ the voltage to frequency conversion techniques, a train of pulses, whose

frequency depends upon the voltage being measured, is generated then the number of pulses appearing in a

definite interval of time is counted. Since the frequency of these pulses is a function of unknown voltage, the

number of pulses counted in that period of time is an indication of the input (unknown) voltage so it

measures true value of input voltage over a fixed measuring period.

101. (C)

Advantages of Semiconductor strain gauges in compare to others are:

1. High gauge factor

2. Low Hysteresis

3. Good frequency response

4. Very small size

Dis advantages of Semiconductor strain gauges in compare to others are:

1. High temperature sensitivity

2. Non linear characteristics

102. (D)

Reference: Exactly same line was discussed in Signal System class notes on page no. 123 as shown below.

103. (A)It is just shifting property.

Reference: Exactly same type of Q.19 in Signal System assignment page no.35

104. (D) For a linear phase system Phase is proportional to frequency

Reference: Phase delay and group delay class notes in signal and system

105. (C)Continuity equation is based upon conservation of charge

Reference: exact Q.42 in Assignment -2 of EDC question no.

106. (A)

107. (A)

Reference: Exactly same line discussed in Signal system class notes page no.247 as shown below

23

108. (C) Here no common portion in ROC is available hence it will not converge.

109. (D) It has zero value so cant be either positive and negative. Reference: Exactly same line was discussed in random variable class notes as shown below

110. (B)

It not following linear and super position property and so it cant be LTI system. Reference: Easy Q Many such type of Qs were discussed in class.

111. (B)

112. (A)

2 2

XY XX x x[m] h[m] [m] h[m] h[m]

24

Reference: Exactly same concept was discussed in Random variable class notes on page no.35 as shown

113. (C)

V VV 4 I 2I 3.6

6 I

Reference: Simple Question based upon super mesh many Qs done in class notes page 6-8

114. (C)

Discrete time LPF is periodic with period 2.

115. (C) t /V

I(t) (1 e )R

It will rise to 0.63 times in 1 time constant and hence time will be equal to L/R=0.5 Sec

Reference: Refer Network assignment chapter-2 Direct Q.37

116. (D) x x x x10 2i 1(3 i ) 2i i 1.4A (By using super mesh equation)

Reference: Simple Question based upon super mesh many Qs done in class notes page 6-8

117. (A) V

IjwL

Reference: Simple and direct Q

118. (C) 0f

QBW

Reference: Exactly same line was discussed in network theory class notes on page no.140 as shown below

119. (D)

Just calculate Ldi

V Ldt

Reference: This is previous year question asked in Electrical and was given in ESE-2015 Test series

120.(*) Number of possible trees are equal to T

A . A where A is reduced incidence matrix.

Answer=8

Reference: Exactly same line discussed in Network theory class notes page no.163 as shown below

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IES Paper 1 Soln