1-MARKS QUESTION ( Q.1 – Q.20)
1.
a.
b.
c.
d.
2.
a.
b.
3.
a.
b.
4.
a.
b.
c.
d.
5.
a.
b.
6.
a.
b.
7.
a.
b.
8.
a.
b.
9.
a.
b.
10.
a.
b.
The depletion layer of p-n junction :
Is of constant width irrespective of the bias
Acts like an insulating zone under reverse bias
Has a width that increase with an increase in forward bias
Is depleted of ions
The p-n junction diode is used as :
An amplifier
c.
A rectifier
An oscillator
d.
A modulator
A semiconductor is formed by :
Co-ordinate bond
c.
Ionic bond
Covalent bond
d.
Metallic bond
In a p-type semiconductor :
Current is mainly carried by holes
Current is mainly carried by electrons
The material is always positively charged
Doping is done by penta-valent material
When a semiconductor is continuously heated, the value of its resistance :
Increase
c.
Increase the decrease
Decrease
d.
Remains unchanged
When then p end of p-n junction is connected to the negative terminal of the battery and the
n end to the positive terminal of the battery, then the p-n junction behaves like :
A conductor
c.
A super conductor
A insulator
d.
A semiconductor
In a semiconductor (Si), the energy gap between the valence and conduction band is :
1.1eV
c.
10eV
5eV
d.
15eV
The band gap in Germanium and Silicon in eV respectively are :
0.7,1.1
c.
1.1,0
1.1,0.7
d.
0,1.1
At 0 K, intrinsic semiconductor behaves as :
A perfect conductor
c.
A semiconductor
A super conductor
d.
A perfect insulator
The forbidden gap in the energy band of germanium at room temperature is about :
1.1eV
c.
0.67eV
0.1eV
d.
6.7Ev
11.
a.
b.
12.
a.
b.
13.
a.
b.
14.
a.
b.
15.
a.
b.
16.
a.
b.
17.
a.
b.
18.
a.
b.
19.
a.
b.
20.
a.
b.
To make p-type semiconductor, the impurity to be mixed with pure germanium will be :
Phosphorus
c.
Antimony
Silver
d.
Aluminum
The energy gap between the valence and conduction band of an insulator is about ;
0.1eV
c.
5.0eV
1.0eV
d.
Zero
By photoelectric effect , Einstein, proved
E= hv
c.
E= mc2
K.E=(1/2)mv2
d.
E= Rhc2/n2
The unit of planck’s constant is :
Joule
c.
joule/m
joule/s
d.
joule-s
The wavelength of a 1 keV photon is 1.24nm. the frequency of 1MeV photon is :
1.24x1015Hz
c.
1.24x1018Hz
2.4x1020Hz
d.
2.4x1024Hz
A photon of energy 8eV is incident on metal surface of threshold frequency 1.6x1015Hz. the
kinetic energy of the photoelectrons emitted( in eV) (take h= 6x10-34 J-s) :
1.6
c.
2
6
d.
1.2
Photon of energy 6eV are incident on a surface of work function 2.1 eV . what is the stopping
potential?
3.5eV
c.
2.7eV
3.9eV
d.
2.8eV
Light of frequency 4v0 is incident on the metal of the threshold frequency v0. .the maximum
kinetic energy of the emitted photo-electrons is :
3hv0
c.
3/2hv0
2hv0
d.
1/2hv0
Photons of energy 6eV are incident on metal surface whose work function if 4eV. The
minimum kinetic energy of the emitted photoelectrons will be :
0 eV
c.
2 eV
1 eV
d.
10 eV
Work function of a metal is 2.51 eV , threshold frequency is :
5.9x1014 cycles/sec
c.
9.4x1014 cycles/sec
6.5x1014 cycles/sec
d.
6.08x1014 cycles/sec
2-MARKS QUESTION (Q.21 – Q.60)
21.
a.
b.
c.
d.
22.
a.
b.
Doping of intrinsic semiconductor is done :
To neutralize charge carriers
To increase the concentration of majority charge carries
To make it neutral before disposal
To carry out further purification
The correct relation between α and β in a transistor is :
β = α/(1-α)
c.
β = (1+α)/α
β = α/(1+α)
d.
β = 1- α
23.The output wave form of full-wave rectifier is :
a.
c.
b.
d.
24. The valence band and conduction band of solid overlap at low temperature, the solid may be :a.
a metal
c. a semiconductor
b.
an insulator
d.
none of these
25. Let ie ,ic, and ib represent emitter current, collector current and base current of a transistor then :
a. ic > ie
b. ib > ic
c.
d.
ic > ib
ie > ic
26. In a transistor configuration β parameter is :
a. Ib/Ic
b. Ic/Ib
c.
d.
Ic/Ie
Ie/Ic
27. The theory associated with secondary wavelets is :
a. Doppler’s effect
b. Special theory of relativity
c.
d.
Huygen’s wave theory
None of these
28. In silicon when phosphorus is doped ………………….is formed :
a. P-type semiconductor
b. n-type semiconductor
c.
d.
p-n junction
none of these
29. An antenna is:
a. Inductive
b. capacitative
c.
d.
resistive above its resonance frequency
none of these
30. for television broadcasting, the frequency employed is normally :
a. 30-300MHz
b. 30-300GHz
c.
d.
30-300kHz
30-300Hz
31. Ozone layer above earth’s atmosphere will:
a.
b.
c.
d.
Prevent infrared radiation from sun reaching earth
Prevent infrared rays reflected from earth from escaping earth’s atmosphere
Prevent ultraviolet rays from sun
Reflect back radio wave
More than one answer is correct (Q. 32- Q.34 )
32. Holes are charge carriers in :
a. Intrinsic semiconductor
b. Ionic solids
c.
d.
P-type semiconductors
Metals
33. A semiconductor is doped with a donor impurity :
a.
b.
c.
d.
The hole concentration increases
The hole concentration decreases
The electron concentration increases
The electron concentration decreases
34. Select the correct statement from the following :
a.
b.
c.
d.
A diode can be used as a rectifier
A diode cannot be used as a rectifier
The current in a diode is always proportional to applied voltage
No one is correct
35. If A=B=1 then in term of Boolean algebra A+B equals :
a. A
b. B
c.
d.
A or B
A+B
36. Binary add of 01101010 + 00001000 + 10000001 + 11111111 is
a. 11011100
b. 11111000
c.
d.
111110010
100001110
37. Binary add of 1011 and 1100 is
a. 00110
b. 0111
c.
d.
10111
10001
38. The decimal value of 000000011111111 is
a. 563
b. 1032
c.
d.
1983
255
39. The binary value of 53 is
a. 000000000101101
b. 101101
c.
d.
110101
000000001
40. Which of the following is acceptor impurity element ?
a. Antimony
b. Gallium
c.
d.
Arsenic
Phosphorus
41. Which of the following semiconductor is electrical positive ?
a. Intrinsic semiconductor
b. P-type semiconductor
c.
d.
N-type semiconductor
None of these
42. When a semiconductor is doped its electrical conductivity :
a.
b.
c.
d.
Increase
Decrease in the direct ratio of the doped material
Decrease in the inverse ratio of the doped material
Remains unchanged
43. In a P-N-P transistor with normal bias :
a.
b.
c.
d.
Only holes cross the collector junction
Only majority carriers cross the collector junction
The collector junction has a low resistance
The emitter-base is forward and collector-base junction is reverse biased
44. For detecting intensity of light we use :
a. Photodiode in forward bias
b. Photodiode in reverse bias
c.
d.
LED in forward bias
LED in reverse bias
c.
d.
Stabilization of voltage
Production of carrier wave
45. Zener diode are used for :
a. Rectification
b. Amplification
46. Transistor was designed by :
a. Edison
b. Fleming
c. lee de forest
d. Shockley
47. Avalanche breakdown in a semiconductor junction diode occurs when :
a.
b.
c.
d.
Forward bias exceeds Zener voltage
Reverse bias exceeds Zener voltage
Forward current becomes too large
The potential barrier is reduced to zero
48. In common base transistor amplifier the current gain is :
a. One
b. More than one
c.
d.
Less than one
Infinite
49. Strength of photoelectric current depends on :
a.
b.
c.
d.
Frequency of incident radiation
Intensity of incident radiation
Angle of incident of radiation
Distance between anode and cathode
50. In photoelectric effect the energy of the emitted electron is :
a.
b.
c.
d.
Larger than that of the incident photon
Smaller than that of the incident photon
Same as that of the incident photon
Proportional to the emission of incident light
51. The photoelectric effect proves that :
a.
b.
c.
d.
Light travels in the form of quanta
Light travels in the form of transverse wave
Velocity of light is infinite
None of these
52. Light of wavelength 5000A’ fall on a metal surface having work-function 1.9 eV . the stopping
potential is :
a. 0.58 V
b. 6.58 V
c.
d.
8.58 V
10.58 V
53. Speed of radio wave is :
a. 300m/s
b. 300000000m/s
c.
d.
180mile/s
400mile/s
54. Layer between 250km to 400km above the earth is called :
a. E-layer
b. A-layer
c.
d.
D- layer
F-layer
55. Area of the signal if the antenna height is 75m.( R= 6400km)
a. 3008km2
b. 1808km2
c.
d.
3018km2
3058km2
56. General propagation of UHF frequency is done by :
a. Ground wave
b. Sky wave
c.
d.
Surface wave
Space wave
57. Optical fiber is :
a. Transmission line
b. Directed wave
c.
d.
Both transmission and directed wave
None of these
58. In a amplitude wave , maximum amplitude voltage is 10V and minimum 2 V THE modulation index
is : M.I = ( Vmax - Vmin )/ ( Vmax + Vmin)
a. 10V
b. 9V
c.
d.
8V
7V
59. Who is present president & vice- president of india :
a. P.D.S Patil & A.P.J. A. KALAM
b. P.D.S. Patil & Nitish kumar
c. P. Mukharjee & Hamid ansari
d. Hamid ansari & P. mukharjee
60. A diode can convert :
a.
b.
c.
d.
A.c . into d.c. but not d.c. into a.c
D.c. into a.c. but not a.c into d.c
A.c. into d.c and d.c. into a.c
Neither a.c int d.c nor d.c. into a.c.