GameChanger Academy

Mechanics

1. Units, Dimensions and Errors

2. Vectors and Scalars

3. Motion in a Straight Line

4. Projectile Motion

5. Newton's Laws of Motion

6. Friction

7. Work, Energy, Power and Collision

8. Circular motion

9. Rotational motion

10. Simple Harmonic Motion

11. Gravitation

12. Elasticity

13. Surface Tension

14. Fluid dynamics and Viscosity

15. Hydrostatics

Heat and Thermodynamics

16. Thermometry

17. Thermal expansion

18. Calorimetry, Change of State and Hygrometry

19. Gas Laws and Kinetic theory of Gases

20. Transmission of Heat

21. Thermodynamics

Sound and Waves

22. Wave

23. Superposition of Waves

24. Stationary/ Standing waves

25. Doppler's effect and Musical sound

Optics

26. Reflection of Plane and Curved Mirrors

27. Refraction at Plane surfaces and Total internal reflection

28. Refraction through prism and Dispersion of Light

29. Refraction through Lenses

30. Chromatic abberation in Lenses, Optical instruments and Human eye

31. Velocity of Light

32. Photometry

33. Wave nature of Light

Electrostatics

34. Charge and Force

35. Electric Field and Potential

36. Capacitance

Electrodynamics

37. Electric current

38. Heating Effect of Current

39. Thermoelectricity

40. Chemical effect of Current

41. Meters

Electromagnetism

42. Properties of Magnets

43. Magnetic effects of Current

44. Electromagnetic induction

45. Alternating current

Modern Physics

46. Cathode rays, Positive rays and Electrons

47. Photoelectric effect

48. X-rays

49. Atomic structure and Spectrum

50. Radioactivity

51. Nuclear physics

52. Semiconductor and Semiconductor devices

53. Diode and Triode valves

54. Logic gates

55. Relativity and Universe

56. Particle physics

Modern Physics

52. Semiconductor and Semiconductor devices

1. In diode when current flows from P to N it is called

[MOE 2010]

Forward biased
Reversed bias
Biassing opposite
Negative biased

2. A certain glass of material with a wide forbidden band between the valence and conduction bands is called

[MOE 2012]

Insulator
conductor
Semiconductor
super-conductor

3. Zener diode are used for

[BP 2017]

rectification
amplification
stabilization of voltage
detector

4. When antimony is doped with silicon, extrinsic semiconductor obtained is

[MOE 2010]

n-type
p-type
n-p-n
p-n-p

5. The silicon semiconductor formed by doping trivalent atoms will be

[MOE 2009]

n-type
p-type
n-p-n type
p-n-p type

6. The energy gap between the conduction band and the valence band of a certain material is 0.7eV. The material is

[KU 2009]

An insulator
A conductor
semiconductor
semimetal

7. What is voltage gain in a common emitter amplifier, where input resistance is 3Ω & load resistance 24Ω, β = 0.6?

[BP 2009]

8. In npn transistor, electron move from

[BP 2011]

base to emitter
collector to emitter
emitter to base
emitter to collector

9. Voltage gain of amplifier depends on

[BP 2012]

load resistance
voltage applied
current
none

10. Electrical conductivity of semiconductor of this type increases with increase in temperature:

[I.E 2012]

P-type semiconductor
N-type semiconductor
Intrinsic semiconductor
None

11. Which of the following is doped with silicon to form N-type semiconductor?

[I.E 2012]

12. When P-N junction diode is forward biased;

[I.E 2012]

increase in barrier potential
decrease in barrier potential
increase in minority carrier current
none

13. If the temperature of a semiconductor is lowered from T₁ to T₂. The resistance of semiconductor

[I.E 2012]

increases
decrease
remains constant
none

14. To a silicon sample traces of aluminium are added as an impurity. The resultant sample would behave like:

[I.E 2010]

conductor
p-type semiconductor
n-type semiconductor
insulator

15. In which of the following transistor amplifier configurations, the voltage gain is highest.

[I.E 2010]

common base
common emitter
common collector
none

16. The current gain in a transistor is 0.98. If the change in emitter current is 5mA. The change in collector current is:

[I.E 2011]

4.9mA
5.1mA
0.96mA
0.19mA

17. Which of the following shows forward biasing?

[I.E 2009]

P-side at higher potential than N-side
N-side at higher potential than P-side
Both at same potential
None

18. Which is correct for a transistor?

[KU 2010]

Collector is reverse biased and emitter is forward biased
Collector and emitter both are forward biased
Emitter is reverse biased and collector is forward biased
Both emitter and collector are reverse biased

19. When p-n junction diode is forward biased the width of depletion layer.

[MOE 2008]

increases
decreases
remains unchanged
None

20. The impurity atoms with which pure silicon should be doped to make an n-type semi-conductor is:

[MOE 2062]

Aluminum
Boron
Indium
Phosphorus

21. Silicon and silver both are cooled from 100°C to 0°C, their conductivity changes as

[MOE 2055]

conductivity of silicon decreases and that of silver increases
conductivity of silicon increases and that of silver decreases
both a and b
none

22. For proper use of a transistor:

[MOE 2053]

Emitter & base are forward biased and base & collector are reverse biased
Both are reversed biased
Both are forward biased
We don't have proper knowledge of using transistor

23. A device for generating an Alternating current of a desired frequency is known as

[T.E. 2004]

Oscillator
Amplifier
Rectifier
Diode

24. The potential barrier in the depletion layer is due to

[T.E. 2008]

Ions
Electrons
Holes
Forbidden band

25. In a semiconductor diode P-side is earthed and N side is applied a potential of -2V the diode shall

[BPKIHS-07]

Breakdown
Conduct partially
Conduct
Not conduct

26. Forbidden energy gap shows the order

[BPKIHS-02]

Conductor < Semi-conductor < Insulator
Semi-conductor < conductor < Insulator
All the same
Conductor = Insulator < semi-conductor

27. In a PN junction diode, when no potential is applied

[BPKIHS-02]

holes diffuse from P to N and electrons from N to P
a small electric field is set up
no effect
holes only diffuse from P to N

28. A transistor is essentially a:

[BPKIHS 05]

current operating device
voltage operated device
power driven device
resistance operated device

29. When P-N junction diode is forward biased and then reverse biased the flow of current is mainly due to

[BPKIHS 2000]

diffusion of electrons in first case and drift velocity in the second case
drift velocity in first case and diffusion of electrons in the second case
diffusion of electrons in both cases
drift velocity in both cases

30. The resistivity of semi conductor depends on

[BPKIHS-06]

atomic nature of semi conductor
atomic reactivity of semi conductor
atomic number of semi conductor
none

31. Which of the following is correct?

[BPKIHS-06]

α = β/(1+β)
β = α/(1-α)
α = β + 1/β
β = α - 1

32. A N-P-N transistor in a common emitter circuit has

[BPKIHS-94]

a low transfer ratio
a low AC current gain
leakage of current independent of temperature
valid Kirchoff's laws

33. The drift current in a P-N junction diode is

[BPKIHS-97]

from the n side to the p side if the junction is forward biased
from the n side to the p side if the junction is reverse biased
from n side to p side
from p side to n side

34. Comparison of conductivity of Ge and Cu when temperature falls from 25°C to 80 K

[BPKIHS 98]

conductivity of Ge increase and Cu decrease
conductivity of both increase
conductivity of Ge decreases and Cu increases
conductivity of both decreases

35. Ge transistor can be operated at a temperature

[BPKIHS 98]

Upto 90°C
Upto 40°C
Above 100°C
Upto 20°C

36. The ratio of electron and hole current in a semiconductor is 4/3 and the ratio of drift velocities of electron and holes is 2/3, then the ratio of concentration of electrons and holes will be

[BPKIHS 98]

37. If a semiconductor has an intrinsic carrier concentration of 1.41×10¹⁶/m³ when doped with 10²¹/m³ phosphorous atoms, then the concentration of holes/m³ at room temperature will be

[BPKIHS 98]

2 × 10²¹
2 × 10¹¹
1.41 × 10¹⁰
1.41 × 10¹⁶

38. The depletion layer in silicon diode is 1µm wide and the knee voltage is 0.6V, the electric field in the depletion layer will be.

[BPKIHS 98]

0
0.6 V/m
1×10⁶ V/m
6×10⁵ V/m

39. Consider the junction diode is ideal. The value of current in the circuit is

[BPKIHS 98]

0
10^-2 A
10^-3 A
10³ A

40. A n-p-n transistor circuit has α = 0.984, if I_C = 2mA, then value of I_B is

[BPKIHS 98]

0.03 mA
0.003 mA
0.66 mA
0.015 mA

41. The electrical conductivity of semiconductor

[BPKIHS 98]

is independent of temperature
decreases with increase of temperature
increases with increase of temperature
first increases and then decreases with increase of temp

42. An n-type semiconductor is

[BPKIHS 98]

negatively charged
positively charged
neutral
may be negatively or positively charged depending on amount of impurity

43. An electric field is applied to semiconductor. Let the number of charge carriers be n and the average drift speed be v. If the temperature is increased.

[BPKIHS 98]

both n and v will increase
n will increase but v will decrease
v will increase and n will decrease
both n and v will decrease

44. Diffusion current in a p-n junction is greater than the drift current in magnitude if

[BPKIHS 98]

the junction is forward biased
the junction is reverse-biased
the junction is unbiased
in no case

45. The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are:

[BPKIHS 98]

drift in forward bias, diffusion in reverse bias
diffusion in forward bias, drift in reverse bias
diffusion in both forward and reverse bias
drift in both forward and reverse bias

46. In a good conductor, energy gap between the conduction band and valence band is

[BPKIHS 98]

infinite
wide
narrow
zero

47. In an n-p-n transistor circuit, the collector current is 10mA. If 90% of the electrons emitted reach the collector

[BPKIHS 98]

I_E = 11.11 mA, I_B = 1.11 mA
I_E = 11 mA, I_B = 1 mA
I_E = 1 mA, I_B = 9 mA
I_E = 9 mA, I_B = 1 mA

48. When the conductivity of a semiconductor is only due to breaking of covalent bond, the semiconductor is called.

[BPKIHS 98]

extrinsic
intrinsic
n-type
p-type

49. Filter circuit

[BPKIHS 98]

eliminates a.c. component
eliminates d.c. component
does not eliminate a.c. component
none

50. Current gain of a transistor in common base model is 0.95. Its value in common emitter mode is

[BPKIHS 98]

0.95
1.5
19
(19)^-1

51. The current gain of a transistor in a common emitter configuration is 40. If the emitter current is 8.2 mA, then base current is

[BPKIHS 98]

0.02 mA
0.2 mA
2 mA
0.4 mA

52. For a common base amplifier, the values of resistance gain and voltage gain are 3000 and 2800 respectively. The current gain will be

[BPKIHS 98]

1.1
0.98
0.93
0.83

53. The value of current in the following diagram will be

[BPKIHS 98]

0 A
10^-2 A
0.025 A
none

54. The forward bias diode is

[BPKIHS 98]

P: +3V, N: 0V
P: 0V, N: +3V
P: -2V, N: 0V
P: 0V, N: -2V

55. Which of the following semiconductor diodes is reverse biased?

[BPKIHS 98]

P: +5V, N: +2V
P: -3V, N: 0V
P: 0V, N: 0V
P: +1V, N: +1V

56. In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector, the base current is

[BPKIHS 98]

36 mA
26 mA
16 mA
6 mA

57. Mercury is cooled to 4K, it behaves as

[IOM 2016]

Semiconductor
Insulator
Superconductor
Conductor

58. When intrinsic semiconductor is doped with impurity then conductivity is:

[KU 2016]

Increases
Decreases
constant
None

59. Forward biasing of p-n junction offers:

[KU 2016]

High resistance
No resistance
Low resistance
Infinite resistance