Electronics Engineering Questions for PSU Recruitment

1. The difference between the number of atoms in a unit cell of a bcc crystal and an fcc crystal is
(a) 1
(b) 2
(c) 4
(d) 6

2. If a small amount of Cu is added to a Ni conductor, then the
(a) resistiviy of Ni will decrease at all temperatures because Cu is a better conductor than Ni
(b) residual resistivity of Ni at low temperatures will increase as Cu atoms act as defect centres
(c) resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects
(d) resistivity of Ni remains unaltered as Cu atoms give the same number of free electrons as Ni atoms

3. For the n-type semiconductor with n = N_P and p = ni ²/N_D the hole concentration will fall below the intrinsic value because some of the holes
(a) dropback to acceptor impurity states
(b) drop to donor impurity states
(c) virtually leave the crystal
(d) recombine with the electrons

4. Match List I (Magnetic materials) with List II (Dipole arrangement in external field) and select the correct answer using the codes given below the Lists:
List I List II

A. Paramagnetic 1. All dipoles are aligned in one preferred direction
B. Ferromagnetic 2. Half of the dipoles are aligned in opposite
direction and have equal magnitudes.
C. Antiferro-magnetic 3. Half of the dipoles (with equal magnitudes) are
aligned in opposite direction to other half having
equal but lower magnitudes.
D. Ferrimagnetic 4. All dipoles have equal magnitudes but are
randomly oriented.
Codes:
A B C D
(a) 4 3. 2 1
(b) 4 1 2 3
(c) 2 1 4 3
(d) 2 3 4 1

5. For an insulating material, dielectric strength and dielectric loss should be
respectively
(a) high and high
(b) low and high
(c) high and low
(d) low and low

6. Match List I (Optical devices) with List II (Electrical/optical characteristics) and select the correct answer using the codes given below Lists:
List I List II
A. LASER 1. Emits monochromatic light of low intensity
B. Solar Cell 2. Consumes electrical power due to the incident light
C. Photo diode 3. Delivers power to a load
D. LED 4. Emits monochromatic light of high intensity
Codes:
A B C D
(a) 4 3 1 2
(b) 3 4 2 1
(c) 4 3 2 1
(d) 3 4 1 2

7. Which one of the following is the best definition of a superconductor?
(a) It is a material showing perfect conductivity and Meissner effect below a critical temperature
(b) It is a conductor having zero resistance
(c) It is a perfect conductor with highest diamagnetic susceptibility
(d) It is a perfect conductor but becomes resistive when the current density through it exceeds a critical value

8. The ac resistance of a forward-biased p-n junction diode operating at a bias voltage ‘V’ and carrying current ‘I’ is
(a) zero
(b) a constant value independent of V and 1
(c) V/I
(d) delta V/ delta I

9. Match List I with List II and select the correct answer using the codes given
below the Lists:
List I List II
A. Drift current 1. Law of conservation of charge
B. Einstein’s equation 2. Electric field
C. Diffusion current 3. Thermal voltage
D. Continuity equation 4. Concentration gradient
Codes:
A B C D
(a) 2 1 4 3
(b) 4 3 2 1
(c) 4 1 2 3
(d) 2 3 4 1

10. Consider the following statements:
If an electric field is applied to an n-type semiconductor bar, the electrons and
holes move in opposite directions due to their opposite charges. The net current is
1. due to both electrons and holes with electrons as majority carriers.
2. the sum of electron and hole currents.
3, the difference between electron and hole current.
Which of these statements is/are correct?
(a) 1 alone
(b) 1 and 2
(c) 2 alone
(d) 3 alone

11. Consider the following circuit configurations:
1. Common emitter.
2. Common base.
3. Emitter follower
4. Emitter follower using Darlington pair.
The correct sequence in increasing order of the input resistances of these
configurations is
(a) 2, 1, 4, 3
(b) 1, 2, 4, 3
(c) 2,1,3,4
(d) 1,2,3,4

12. Match List I With List II and select the correct answer using the codes given
below the Lists:
List I List II
(Devices) (Property)
A. Silicon diode 1. High frequency applications
B. Germanium diode 2. Very low reverse bias saturation current
C. LED 3. Low forward bias voltage drop
D. PIN diode 4. Cut-off wavelength

Codes:
A B C D
(a) 1 3 4 2
(b) 2 4 3 1
(c) 1 4 3 2
(d) 2 3 4 1

13. The depletion layer across a p⁺ – n junction lies
(a) mostly in the p⁺ region
(b) mostly in the n – region
(c) equally in both the p⁺and n – regions
(d) entirely in the p⁺ region

14. Match List I (Biasing of the junctions) with List II (Functions) in respect of the BJT and select the correct answer using the codes given below the Lists:
List I List II
A. E-B junction forward bias and C-B 1. Very low gain amplifier
junction reverse bias
B. Both E-B and C-B junctions forward bias 2. Saturation condition
C. E-B junction reverse bias and C-B 3. High gain amplifier
junction forward bias
D. Both E-B and C-B junctions reverse bias 4. Cut-off condition
Codes:
A B C D
(a) 2 3 1 4
(b) 3 2 1 4
(c) 3 2 4 1
(d) 2 3 4 1

15. Match List I (Structures/characteristics) with List II (Reasons) in respect of JFET and select the correct answer, using the codes given below the Lists:
List I List II
A. n-channel JFET is better than p- 1. Reverse bias increases along the
channel JFET channel
B. Channel is wedge shaped 2. High electric field near the drain
and directed towards source
C. Channel is not completely closed at 3. Low leakage current at the gate
pinch-off terminal
D. Input impedance is high 4. Better frequency performance since Mu(n)>> Mu(p)

Code:
A B C D
(a) 4 1 2 3
(b) 4 2 1 3
(c) 3 1 2 4
(d) 3 2 1 4

16. Consider the following statements:
A four-layer PNPN device having two gate leads can be turned on by applying a
1. positive current pulse to the cathode gate.
2. positive current pulse to the anode gate.
3. negative current pulse to the anode gate.
4.’ negative current pulse to the cathode gate.
Which of these statements is/are correct?
(a) 1 alone
(b) 1 and 3
(c) 2 alone
(d) 2 and 4

17. Almost all resistors are made in a monolithic integrated circuit
(a) during the emitter diffusion
(b) while growing the epitaxial layer
(c) during the base diffusion
(di) during the collector diffusion

Directions:
The following items consist of two statements, one labelled the ‘Assertion A’ and the other, labelled the ‘Reason R’ You are to examine these two statements and decide if the ‘Assertion A’and the ‘Reason R’ are individually true and if so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using the codes given below and mark your Answer Sheet accordingly:
Codes
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is NOT a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

18. Assertion (A) : BaTiO₃ is a piezoelectric material and is used in a record player.
Reason (R) : In a piezoelectric transducer, stress induces polarization and an electric
field strains the material.

19. Assertion (A) : Hall crystal can be used as a multiplier of two signals.
Reason (R) : Hall voltage is proportional to the currents or voltages applied in
perpendicular directions across the Hall crystal.

20. Assertion (A) : The hybrid pi model of a transistor can be reduced to its h-parameter
model and vice-versa.
Reason (R) : Hybrid pi and h-parameter models are inter-related as both of them
describe the same transistor.

21. Assertion (A) : When light falls at the junction of a p-n photo diode, its P side becomespositive and N side becomes negative.
Reason (R) : When a photo diode is short-circuited, the current in the external circuit
flows from the P-side to the N-side.

22. Assertion (A) : Prescalers are used in digital counters to extend the frequency range.
Reason (R) : Prescalers are simple dividing circuits and as such do not have the
high frequency limitation of digital counters.

23. Assertion (A) : CRTs, used in TV receivers are of electrostatic deflection type and
those used in oscilloscopes are of magnetic deflection type.
Reason (R) : TV receivers need a large screen to view pictures, whereas accuracy
is the main consideration in oscilloscopes.

24. Assertion (A) : Alnico is commonly used for electromagnets.
Reason (R) : Alnico has low hysteresis loss.

25. Assertion (A) The solution of Poisson’s equation is the same as the solution of
Laplace’s equation.
Reason (R) : Laplace’s equation is a special case of Poisson’s equation for source-
free regions.

26. Assertion (A) : The fundamental loop of a linear directed graph contains four twigs
and two links corresponding to a given tree.
Reason (R) : Ina linear directed graph, a link forms a closed loop.

27. Assertion (A) : TI ‘zero-state’ response of a linear constant-parameter continuous-
time system can have components having the ‘natural frequencies of the system.

Reason (R) : The ‘forced frequency components in the response of the state for any
given input may not add up to the given zero initial value of the state.
The ‘natural frequency components may be needed to bridge the gap.

28. In a two-terminal network, the open-circuit voltage measured at the given terminals by an electronic voltmeter is 100 V. A short-circuit current measured at the same terminals by an ammeter of negligible resistance is 5 A. If a load resistor of 80 Ohm is connected at the same terminals, then the current in the load resistor will be
(a) 1A
(b) 1.25A
(c) 6A
(d) 6.25A

29 Consider the following statements:
1. Tellegen’s theorem is applicable to any lumped network.
2. The reciprocity theorem is applicable to linear bilateral networks.
3. Thevenin’s theorem is applicable to two-terminal linear active networks.
4. Norton’s theorem is applicable to two-terminal linear active networks.
Which of these statements are correct?
(a) l,2 and 3
(b) 1,2,3 and 4
(c) l,2 and 4
(d) 3 and 4

30. The network has 10 nodes and 17 branches. The number of different node pair voltages would be
(a) 7
(b )9
(c) 10
(d) 45

31. Consider the following statements:
A 3-phase balanced supply system is connected to a 3-phase unbalanced load.
Power supplied to t4is load can be measured using
1. two wattmeters.
2. One wattmeter.
3. three wattmeters.
Which of these statements is/are correct?
(a) 1 and 2
(b) 1 and 3
(c) 2 and 3
(d) 3 alone

32.A capacitor used for power factor correction in single-phase circuit decreases
(a) the power factor
(b) the line current
(c) both the line current and the power factor
(d) the line current and increases power factor

33. Consider the following statements:
If a network has an impedance of (i -j) as a specific frequency, the circuit
would consist of series
1. R and C
2. R and L
3. R,L and C
Which of these statements are correct?
(a) 1 and 2
(b) 1 and 3
(c) 1, 2 and 3
(d) 2 and 3

34. A network contains only independent current sources and resist6rs. If the values
of all resistors are doubled, the values of the node voltages
(a) will become half
(b) will remain unchanged
(c) will become double
(d) cannot be determined unless the circuit configuration and the values of the resistors
are known

35. Consider the following statements regarding the fundamental component f1, (t)
of an arbitrary periodic signal f(t):
It is possible for
1. the amplitude of f1 (t) to exceed the peak value of f(t).
2. f1 (t) to be identically zero for a non-zero f(t).
3. the effective value of f 1(t) to exceed the effective value of f(t).
Which of these statements is/are correct?
(a) 1 alone
(b) 1 and 2
(c) 2 and 3
(d) 1 and 3

36. Two coils have .elf-inductances of 0.09 H and 0.01 H and a mutual inductance of
0.015 H. The coefficient of coupling between the coils is
(a) 0.06
(b) 0.5
(c) 1.0
(d) 0.05

37. A transmission line having 50 Ohms impedance is terminated in a load of (40 +j
30)Ohms . The VS WR is
(a) j 0.033
(b) 0.8+j 0.6
(c) 1
(d)2

38. A vertical wire of 1 m length carries a current of 1 A at 10MHz. The total radiated
power is nearly
(a) 0.13W
(b) 0.88W
(c) 7.3W
(d) 73W

39. A cavity resonator can be represented by
(a) an LC circuit
(b) an LCR circuit
(c) a lossy inductor
(d) a lossy capacitor

40. The skip distance is
(a) same for each layer
(b) independent of frequency
(c) independent of the state of ionisation
(d) independent of transmitted power

Answers :

1	b
2	c
3	d
4	b
5	c
6	c
7	a
8	d
9	b
10	b
11	c
12	d
13	b
14	b
15	a
16	a
17	a
18	a
19	d
20	a
21	b
22	a
23	d
24	a
25	d
26	d
27	b
28	a
29	b
30	b
31	b
32	d
33	b
34	c
35	a
36	b
37	d
38	d
39	a
40	a