MCQ in Electronics

1. Diamond is a paramagnetic material.

A. True

B. False

2. Which capacitor-store higher amount of energy?

A. Air capacitor

B. Paper capacitor

C. Mica capacitor

D. Plastic film capacitor

3. Above ferroelectric curie temperature, spontaneous polarization in ferroelectric materials becomes stronger.

A. True

B. False

4. In paramagnetic materials

A.permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible

B. permanent magnetic dipole do not exist

C. permanent magnetic dipoles exist and the interaction between neighbouring dipoles is very strong

D. permanent magnetic dipole moment may or may not exist

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5. Assertion (A): Atomic number of sodium is 11.Reason (R): Sodium has a body centred cubic lattice.

A. Both A and R are true and R is correct explanation of A

B. Both A and R are true but R is not correct explanation of A

C. A is true but R is false

D. A is false but R is true6. The conductivity of

intrinsic semiconductor is given by

A. eni(μp - μn)

B.eni(μp + μn)

C. ni(μp + μn)

D. ni(μpμn)

7. The core of a coil has a length of 10 cm. The self inductance is 8 mH. If the core length is

doubled, all other quantities remaining the same, the self inductance will be

A. 32 mH

B. 16 mH

C. 8 mH

D. 4 mH

8. The minority carrier life time and diffusion constant in a semiconducting material are 100 μs and 100 cm2/s respectively. The diffusion length of carriers is

A. 0.1 cm

B. 0.01 cm

C. 0.0141 cm

D. 1 cm

9. Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature.

Reason (R): The orientation polarization is independent of temperature.




D. A is false but R is true

10. Two materials having temperature coefficients of 0.004 and 0.0004 respectively are joined in series. The overall temperature coefficient is likely to be

A. 0.08 B. 0.04

C. 0.001 D. 0.0001

11. The number of valence electrons in pentavalent impurity is

A. 5 B. 4

C. 3 D. 1

12. If the diameter of a wire is doubled, its current carrying capacity becomes

A. one-fourth

B. half

C. twice

D. four times

13. The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is

A. Ohm's law

B. Gauss law

C. Ampere's law

D. Biot-Savart law

14. Assertion (A): Silicon is less sensitive to changes in temperature than germanium.

Reason (R): Cut in voltage in silicon is less than that in germanium.





15. Material which lack permanent magnetic dipoles are known as

A. paramagnetic B.diamagnetic

C. ferromagnetic D. ferrimagnetic

16. A parallel plate capacitor has its length, width and separation doubled. It fringing effects are neglected, to keep the capacitance same, the dielectric constant must be

A.halved

B. kept the same

C. doubled

D. made 4 times


17. Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by 90°.

Reason (R): When subjected to ac fields, the dielectric constant can be expressed as ∈'r - j∈"

r.






18. In atomic physics, a state with l = 0 is called p state.

A. True B.False


19. If a sample of germanium and a sample of silicon have the same impurity density and are kept at room temperature

A. both will have equal value of resistivity

B. both will have equal negative resistivity

C. resistivity of germanium will be higher than that of silicon

D. resistivity of silicon will be higher than that of germanium


20. When an electric field E is applied to solid and liquid insulating materials, the internal field Ei acting at the location of atom is such that

A. Ei = E

B. Ei > E

C. Ei < E

D. Ei may be equal to or less than E

21. Which element exhibits the property of inertia?

A. Resistance

B. Capacitance

C. Inductance

D. Both resistance and inductance


22. For a permanent magnetic material

A.the residual induction and coercive field should be large

B. the residual induction and coercive field should be small

C. area of hysteresis loop should be small

D. initial relative permeability should be high


23. In a coaxial cable, braided copper is used for

A. conductor B.shield

C. dielectric D. jacket


24. The hysteresis phenomenon in ferromagnetic materials exists at all temperatures.

A. True B.False


25. Assertion (A): Magnetic susceptibility of diamagnetic materials is much less than that of paramagnetic materials.

Reason (R): For diamagnetic as well as paramagnetic materials, μr is nearly equal to 1.





26. The attraction between the nucleus and valence electron of copper atom is

A. zero

B.weak

C. strong

D. either zero or strong


27. If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then

A. the majority carrier density is doubled

B. the minority carrier density is doubled

C. the minority carrier density becomes 4 times the original value

D. both the majority and minority carrier densities double


28. There is no hysteresis phenomenon is any dielectric material.

A. True B.Fals

e


29. The units of μ0 and μr are

A. H/m for both

B. H/m for μr and no units for μ0

C. H/m for μ0 and no units for μr

D. Wb/m for μ0 and no units for μr


30. In metals the valence electron wave functions are strongly perturbed by the presence of neighbouring atoms.

A. True B. False

31. For a paramagnetic material, susceptiblity increases with increasing temperature.

A. True B.False


32. Hydrogen is used in

A. large size transformers

B. MCB

C.large size generators

D. circuit breakers


33. Assertion (A): Ferroelectric materials have spontaneous polarization.

Reason (R): Above curie temperature, ∈ = for ferro-electric materials.






34. If e is the charge of an electron, R is the radius of its orbit and ω is the angular velocity of electron, the magnetic dipole moment μm of the orbit is |μm| = eωR2.

A. True B.False


35. If ∈r' and ∈r" are the real and imaginary parts of complex dielectric constant ∈r, and δ is the loss angle. Then

A.

B.

C. tan δ = ∈'∈"D. tan δ = 1 - ∈'

36. Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface.

Reason (R): Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT.






37. At room temperature, the current in intrinsic semiconductor is due to

A. holes

B. electrons

C. ions

D.holes and electrons


38. Ferroelectric materials are those which

A. cannot be polarized

B.have a permanent polarization

C. have e equal to zero

D. have μp = 0


39. Assertion (A): Power loss in a conductor of resistance P = I2R.

Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE.






40. Assertion (A): For Diamond, μr = 1

Reason (R): Diamond is a diamagnetic material.





41. If n denotes principal quantum number, the angular quantum number l = 0, 1... (n - 1).

A. True B. False


42. Assertion (A): In a perfect capacitor, the current density is given by ω ∈0E0∈'rcos(ωt +

90°), where ∈r' is real part of dielectric constant.

Reason (R): In a perfect capacitor, dielectric losses are zero.






43.

Assertion (A): For a solenoid having N turns, .

Reason (R): For all magnetic materials, B increases linearly with I.






44. Assertion (A): From the slope of the line in Figure, we can find permanent dipole moment of the molecules.

Reason (R): Total polarization of a polyatomic gas is given by P = N(e + i + μ2p / 3kT)E.






45. Assertion (A): If E is available energy state eV and EF is Fermi level, then probability of energy state E being occupied = 0.5.

Reason (R): .





46. If a piece of wood is placed in a magnetic field

A.the magnetic field will not be affected

B. the magnetic lines of force will bend towards the piece

C. the magnetic lines of force will bend away from the piece

D. the flux may increase or decrease


47. The apparent capacitance at a high angular frequency ω of an air cored capacitor having capacitance C and inductance L is given by

A.

B.

C.

D.


48. The number of valence electrons in donor impurity are

A. 5 B. 4

C. 3 D. 1


49. In a true valence crystal, the bonding between the atoms is accomplished by the sharing of valence electrons.

A. True B. False


50. Which of the following are donor impurities?

1. Gold2. Phosphorus3. Boron4. Antimony5. Arsenic6. Induim

Select the correct answer using the following codes

A. 1, 2, 3

B. 1, 2, 4, 6

C. 3, 4, 5, 6

D. 2, 4, 5

================================ Material and components section 2 ============

1. In crystalline solids, atoms are stacked in a regular manner.

A. True B. False


2. The temperature below which certain materials are antiferromagnetic and above which they are paramagnetic is called

A. Weiss temperature

B. Curie temperature

C.Neel temperature

D. None of the above


3. In metals, the average drift velocity of electron per unit field is called mobility.

A. True B. False


4. Ferrites have

A. a low copper loss

B. low eddy current loss

C. low resistivity

D. higher specific gravity compared to iron


5. In intrinsic semiconductors, the number of free electrons is equal to the number of mobile holes.

A. True B. False

======================================================================

PSU Sample Question Paper 1 Electronics mcqs Add comments

Dec252011

Multiple choice Questions

1. The velocity of sound is the least in which of the following medium:

1) Air 2) Water 3) Wood 4) Vacuum

2. Two amplifier stages have voltage gains of 100 and 200. The total decibel voltage gain of

the cascaded amplifiers is:

1) 46 dB 2) 86 dB 3) 66 dB 4) 106 dB

3. In the circuit shown, what is the minimum value of RL for which the output voltage will

remain constant?

1) 15 W 2) 24 W 3) 27 W 4) 45 W

4 If 1/10th of the total current is to pass through a galvanometer of resistance G W, then the

shunt resistance should be:

1) G/99 W 2) G/9 W 3) G/10 W 4) Gx9 W

5

In the circuit shown, each condenser has a capacitance of 1mF. The equivalent

capacitance between P and Q is:

1) 3 mF 2) 6 mF 3) 1 mF 4) 1/3 mF

6. In an electric circuit, the applied voltage is E=100 Sin (314t) V and the resultant current is I

= 5 Sin (314t + p/3). Then, the circuit is comprised of:

1) L and C 2) L only 3) R and C 4) R and L

7 At any frequency much higher than the resonant frequency of a series resonance circuit,

the angle of impedance Z approaches:

1) -90° 2) +90° 3) 0° 4) 180°

8. An indirectly heated pentode has how many pins?

1) 5 2) 6 3) 7 4) 8

9 The binary number that follows 0110 1111 is:

1) 0110 1100 2) 0111 0000 3) 0111 1000 4) 0110 1110

10. A transformer has an iron loss of 300 W and full load copper loss of 1200 W. At what

percentage of full load does the efficiency become maximum?

1) 80% 2) 60% 3) 50% 4) 25%

11 In a three phase, four wire circuit, the line currents in the R, Y and B phases are 1, 2 and

1 A respectively. What is the current in the neutral conductor?

1) 1 A 2) 2 A 3) 3 A 4) 4 A

12 A FM transmitter operating at 104 MHz is modulated with 5 kHz tone and the maximum

deviation is 75 kHz. Total bandwidth occupied by the FM transmitter will be:

1) 150 kHz 2) 160 kHz 3) 170 kHz 4) None of these

13. What is the aspect ratio in conventional Television?

1) 2:1 2) 3:2 3) 4:3 4) 5:4

14 What is the type of modulation adopted for the Chrominance signal in TV?

1) Amplitude modulation 2) Frequency modulation

3) Phase modulation 4) Quadrature Amplitude modulation

15. A 10 kW transmitter is connected to an antenna and the reflection coefficient observed on

the transmission line is 0.6. The power radiated by the antenna is:

1) 10 kW 2) 3.6 kW 3) 6.4 kW 4) None of these

16. Transmission in short wave is characterised by the following:

1) It takes place by sky wave. 2) Propagation is by reflection from ionosphere.

3) It is subject to severe fading. 4) All of these.

17. Reception of a signal through direct wave depends upon the following:

1) Height of the transmitting antenna 2) Height of the receiving antenna

3) Distance between the transmitter and receiver 4) All the above

18. Which of the following diodes exhibits negative resistance phenomenon?

1) Zener Diode 2) Ordinary Diode 3) Tunnel Diode 4) PIN Diode

19. Which has the longest wave length?

1) Microwave 2) X-ray 3) Ultraviolet ray 4) Infrared ray

20. An infinite line of characteristic impedance Zo is terminated by an impedance ZL. What

is its input impedance?

1) Infinity 2) Zo 3) ZL 4) (Zo.ZL)1/2

Answers of the above problems :

Q.No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Ans. 4 2 4 2 1 3 2 3 2 3 1 2 3 4 3 4 4 3 1 2


Dec262011

1. Three 100W non-inductive resistors, when connected in star across 400 V, 50 Hz, 3 phase

consumes 1600 W. When one of the resistances becomes open, the power consumption is

reduced by:

a) half b) one third c) two third d) one fourth

2. The power input to a three phase induction motor is 62 kW. The stator loss is 2 kW. If the

rotor is running with a slip of 5%, the total copper loss in the rotor will be:

a) 500 W b) 1000 W c) 1500 W d) 3000 W

3. A transformer has an iron loss of 250 W and full-load copper loss of 1000 W. At what

percentage of full-load, the efficiency becomes maximum:

a) 70% b) 66% c) 50% d) 25%

4. Operational amplifier can amplify:

a) AC signals only b) DC signals only

c) Both AC and DC signals d) All of the above

5. Adjacent channel rejection of a receiver is determined by its:

a) Fidelity b) Noise figure c) Selectivity d) Sensitivity

6. In a three input NAND gate, one input is low. The output will be:

a) Low b) Will depend upon other two inputs

c) High d) None of the above

7. If the conduction in the anode circuit takes place for less than 180o of the input cycle, the

amplifier is classified as:

a) Class A b) Class B c) Class C d) Super Class

8. 500 MHz falls in the;

a) HF Band b) VHF Band

c) UHF Band d) SHF Band

9. The signals sent by the TV transmitter to ensure correct scanning in the receiver are called:

a) Sync b) Chroma c) Luminance d) Video

10. A frequency modulated signal, which is modulated by a 3 kHz sine wave swings between

100.02 MHz and 99.98 MHz. The modulation index of the signal will be:

a) 20/3 b) 40/3 c) 10/3 d) 5/3

ANSWERS

1. A 2. D 3. C 4. D 5. C 6. C 7. D 8. C 9. C 10. A


Dec252011

1 Which of the following is not true for common collector amplifier?

o It offers high input impedance. b) It offers low output impedance.

o It offers wide band width. d) It offers a large gain.

2. Which of the following is not true with respect to negative feedback?

o It increases gain. b) It improves distortion.

c) It improves signal to noise ratio. d) It improves bandwidth.

3.If the conduction in the anode circuit takes place for less than 180o of the input cycle, the

amplifier is classified as:

a) Class A b) Class B c) Class C d) Class D

4. The following network will act as a

http://www.mcqs.vacau.com/paper-3/#respond

http://www.mcqs.vacau.com/category/mcqs-paper/electronics/

http://www.mcqs.vacau.com/paper-3/

a) Low pass filter b) High pass filter

c) Band pass filter d) Band stop filter

5. In Satellite Broadcasting, the down link frequency in C band range is

a) 2.5 GHz to 2.7 GHz b) 3.7 GHz to 4.2 GHz

c) 4.5 GHz to 4.8 GHz d) 11.7 GHz to 12.2 GHz

6. In a 100 kW AM transmitter, if the carrier is modulated with 100% modulation index, power

in the lower side band will be:

a) 100 kW b) 50 kW c) 25 kW d) 12.5 kW

7. The ratio of reflected power to incident power is

a) Reflection Co-efficient b) (Reflection Co-efficient)2

c) VSWR d) (VSWR)2

8. The equation relating VSWR with reflection coefficient is

a) b)

c) d)

9. The amount of pre-emphasis given to the audio signal in AIR in FM broadcasting is

a) 25 msec. b) 50 m sec c) 75 m sec. d) 100 m sec.

10. The characteristic impedance of free space is

a) 50 ohms b) 120 ohm c) 377 ohms d) 440 ohms

11. Which of the following is not expressed in watt?

a) V2/R b) I2R c) VxI d) V/I

12. 4 mF is same as

a) 0.004 nF b) 40 nF c) 400 nF d) 4000 nF

13. An electronic fan regulator

a) is a current divider b) voltage divider

c) varies angle of conduction of ac wave d) None of the above

14 An ammeter has 1 A range and has a resistance of 10 W. To measure 10 A current with

this meter, we shall use a resistance

o more than 10 ohms in series b) less than 10 ohms in series

c) more than 10 ohms in parallel d) less than 10 ohms in parallel

15. Which of the following acts as an open circuit to d.c?

a) Diode b) Inductor c) Capacitor d) All the above

Answers:

12 3 4 5 6 7 8 9 10 11 12 13 14 15

d a c b c c b b b c d d c d c

. Fill in the blanks:

Secondary of a current transformer should never be ____________.

____________.

The equipment required for maintenance of a wet battery is ____________.

All electrical installations should be tested for good insulation at least once every

__________.

Stock of Carbon Tetrachloride should be maintained in ______________ register.

The refrigerant in an a.c. plant gets converted from gaseous state to liquid state in the

____________.

When a circuit breaker is drawn out of the rack, the connection spout shutters should be

____________.

……………………………..

A scientific tool for monitoring the progress of a Project is ____________.

Spurious power emitted by transmitters can be judged with the help of a ____________.

Answers:

1. Open Circuited 2. ………………… 3. Hydrometer

4. Six months 5. S150 6. Condensor

7. ………………… 8. 48 9. PERT Chart

10. Spectrum Analyzer

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MCQ in Electronics