TEST 8

PPSC PHYSICS
LASER
ELECTRONICS
NUCLEAR PHYSICS
1) Idea of stimulated emission was first given by .
(a) Schrodinger (b) Bohr
(c) de-Broglie (d) Einstein
2) The population inversion is not achievable in level laser system.
(a) Three
(b) Two
(c) Four
(d) Five
3) Pumping requirement is less in level laser system.
(a) Three (b) Four
(c) Five (d) Two
4) The mean lifetime of metastable state is time greater than mean lifetime
of excited state.
(a) 105
(b) 103
(c) 108
(d) 101
5) The first visible laser formed was .
(a) CO2 laser (b) Zero
(c) Excimer (d) Ruby
6) The unit of laser gain coefficient are .
(a) J m (b) m-1
(c) Dimensionless (d) m
7) Most commonly used laser transition of He-Ne laser is:
(a) 632.8 nm
(b) 543 nm
(c) 1.06 μm
(d) 332 nm
8) Gas lasers are usually pumped:
(a) Optically
(b) Dynamically
(c) Magnetically
(d) Electrically
9) Laser broadening mechanisms are in number.
(a) Two
(b) Three
(c) Four
(d) Five
10) In pulsed lasers, the mechanism for generating powerful pulses is called
.
(a) Gaussian broadening
(b) Q-switching
(c) Frequency hopping
(d) Lorentzian wave-shaping
11) Coherence is of types.
(a) Two
(b) Three
(c) Infinite
(d) Depends on type of laser
12) Which has the highest brightness?
(a) Sun (b) Nd:glass laser
(c) Q-switch ruby laser (d) He-Ne laser
13) Gaussian lineshape is due to broadening.
(a) Critical (b) Homogeneous
 (c) Sustained (d) Inhomogeneous
14) The devices which convert DC to AC are usually referred as:
(a) Transformers (b) Inverters
(c) Amplifiers (d) Rectifiers
15) To maintain constant voltage at output, the devices used are:
(a) Regulators (b) Operational amplifiers
(c) Integrated circuits (d) Transistors
16) Which of the following is called emitter follower?
(a) Common collector amplifier (b) Common base amplifier
(c) Common emitter amplifier (d) Common gate amplifier
17) There are hybrid parameters which characterize a two port network.
a. Five
b. Three
c. Two
d. Four
18) Which uses positive feedback?
a. Oscillators
b. Inverting amplifier
c. Non-inverting amplifier
d. Rectifiers
19) Forward resistance of a diode decreases when charge carriers are increased, this
is called .
(a) Early effect (b) Injection modulation
(c) Resistography (d) Dynamic modelling
20) FETs which have built in channel are called:
a) Enhancement mode
b) Complementary mode
c) Depletion mode
d) Supplementary mode
21) Two chips of silicon are doped as N type and P type respectively with equal
doping ratio.
A. P type is more conductive
B. Both are equally conducting
C. N type is more conducting
D. Both are equally resistive
22) Which is operated in reverse breakdown region?
A. LED
B. Photodiode
C. Zener diode
D. PIN diode
23) For operating a BJT in amplifier mode, it must operate in region.
A. Cutoff
B. Saturation
C. Active
D. Breakdown
24) The devices which can be used in high frequency switching are:
A. BJTs
B. MOSFETs
C. Op-Amps
D. Regulators
25) The multivibrator which has two stable states is called multivibrator.
A. Monostable
B. Astable
C. Bi-stable
D. Schmitt
26) The highest efficiency for large signal amplifiers is for amplifiers.
A. Class A
B. Class B
C. Class AB
D. Class C
27) The amplifier which has infinite common mode rejection ratio is called
amplifier.
A. Differential
B. Linear
C. Non-linear
D. Direct coupled
28) A converter which increases DC level at output is called regulator.
A. Boost
B. Buck
C. Inverting
D. Linear
29) The signal which is to be transferred through modulation is called signal.
A. Modulating
B. Carrier
C. Modulated
D. Agitated
30) Elementary particles which are confined with the help of strong force are called
.
A. Hyperons
B. Quarks
C. Leptons
D. Photons
31) Induced nuclear reactions are discovered by .
A. Einstein
B. Bohr
C. Rutherford
D. J. J. Thomson
32) Alpha decay can be well understood by using model.
A. Shell
B. Bubble
C. Liquid drop
D. Blast
33) Ratio of decay probability per unit time is called .
A. Activity
B. Decay constant
C. Internal conversion
D. Auger effect
34) Nuclear matter is times more dense than atomic matter.
A. 105
B. 1015
C. 1020
D. 1045
35) Π-mesons are of types.
A. Two
B. Four
C. Three
D. Five
36) Exchange quanta for weak nuclear force are:
A. Quarks
B. Pions
C. Gravitons
D. W & Z bosons
37) Higg’s bosons get their mass by .
A. Self-interaction
B. Interacting with gauge bosons
C. Interacting with leptons
D. Interacting with gellatical mass
38) Which has the shortest wavelength?
A. Gamma rays
B. X-rays
C. UV-rays
 D. IR waves
39) Helicity of neutrino is .
A. -1
B. 0
C. 1/2
D. Complex
40) Which are used to exchange colour force between quarks of nucleons?
A. Bosons
B. Gluons
C. Higg’s particle
D. Gravitons