Paper for Entry Test Preparation
Physics 2nd year Chapter No. 18
Total marks:- 160 Time
allowed 25 minutes
Note:- Fill
the appropriate answer of the following questions in the answer sheet. Double
filling and erasing is not allowed. Each question carries equal marks and for
each wrong answer minus one is awarded.
1) The use of ships in electrons is described in the
form of:
a)
Yellow boxes b) Black
boxes c) Red boxes d) White boxes
2) AT room temperature, crystal of germanium, in its
pure form, act as:
a)
A conductor b) A
semiconductor c) An
insulator d) Non of
all
3) An outer most orbit represents stable
configuration if it possesses:
a)
4 electrons b) 8
electrons c) 12
electrons d) 16
electrons
4) Majority charge carriers in the p-region of p-n
junction are:
a)
Electrons b)
Positrons c)
Holes d)
Neutrons
5) When phosphorous is added as an impurity in
germanium, there is an increase in:
a)
Free electron in Ge b) Holes
in Ge c) Positrons
in Ge d) Non of all
6) Depletion region is the region around the p-n
junction and:
a)
Bs charges less b)
Contains electrons as charge carriers
c)
Contains protons as charge carriers d)
Contains holes as charge carriers
7) In a p-n junction, the current flows due to:
a)
Free electrons only b) Holes
only c) Both (a)
and (b) d) Non of all
8) In the forward biased situation, the current
flowing across the p-n junction is a few:
a)
Amperes b)
Milli amperes c)
Micro amperes d) Pic
amperes
9) In the forward biased situation, as the biasing
voltage is increased, the current:
a)
Does not change b) Also
increases c) Decreases d) May by (b) or (c)
10) In reverse-biased p-n junction, the reverse
current is due to flow of:
a)
Minority charge carriers b) Majority
charge carriers c) Free es-
from p to n region d) Both (a) and (c)
11) In the symbol of p-n junction, the vertical line
represents:
a)
The n-region and is known as anode b)
The n-region and is known as cathode
c)
The p-region is known as anode d)
The p-region and is known as cathode
12) Conversion of A.C into D.C is called:
a)
Rectification b)
Amplification c)
Electric induction d) Magnetic induction
13) The semiconductor diode has the property of:
a)
Zero conduction b) One
way conduction c) Two way conduction d) Amplification
14) An LED can be made from:
a)
Silicon b)
Gallium arsenide c)
Gallium arsenide phosphide d) Both (a)
and (b)
15) The reverse current increases with the intensity
of light incident on the p-n junction of:
a)
An ordinary diode b)
Photovoltaic cell c)
Photodiode d) LED
16) The number of LED’s needed to display all the
digits is:
a)
Four b)
Five c)
Nine d)
Six
17) A Led works in the situation of:
a)
Forward bias and emits a photon of invisible light b) Reverse bias and absorbs a photon of visible light
c)
Reverse bias and emits a photon of invisible light c) Forward bias and emits a photon of visible light
18) Gallium arsenide is a semiconductor and is used
in making:
a)
Photovoltaic cell b)
Photodiode c) LED d) Both (a)
and (c)
19) A LED emits light when it is:
a)
Forward biased b)
Reverse biased c) Operated without battery d) Operated with heat
20) Current gain of a transistor is calculated by:
a)
Ib / Ic b) Ic
/ Ib c) Ib / Ie d)
Ie / Ic
21) In order that a transistor act as a switch, a
large positive potential is applied across its:
a)
Base emitter terminals b) Base
collector terminals c) Collector
emitter terminals d) Both (a) and (b)
22) An electronic computer is basically a vast
arrangement of electronic switched which are made from:
a)
Resistors b) Transistors c) N-type crystals d) Capacitors
23) Due to high value of input resistance of op-amp,
the value of current flowing b/w two input terminals is practically:
a)
Large b)
Zero c)
Very much large d) All
are correct
24) The gain of an op-amplifier:
a)
Depends upon its internal structure b)
Is
independent of two externally connected resistances
c)
Both (a) and (b) d)
Non of all
25) The number of input terminals of an op-amp is:
a)
One b)
Two c)
Three d)
Four
26) Op-amp has been discussed as comparator of:
a)
Distances b)
Voltages c)
Velocities d)
Magnetic fields
27) LDR means:
a)
Low degree resonance b) Light
dependent resistance c) Laser detection
rule d) Limit
of depletion region
28) In the circuit of comparator used as night
switch, the numbers of potential dividers are:
a)
Two b)
Three c)
One d)
Four
29) A digital system deals with quantities which has
discrete values:
a)
Two in number b) One in
number c) Three in
number d) Four in number
30) Boolean algebra is bases on the following
operation:
a)
AND, OR b) AND,
NOT c) OR, NOT d) Both (a) and (b)
31) The circuit which implement certain operation
are called:
a)
A.C. circuits b)
Analog circuits c)
Logic gates d)
Steel gates
32) IN AND gate, the out put is 1 if:
a)
Both input are 0 b) Both
input are 1 c) Only one
input is 0 d) Both (a) and
(b)
33) A two input NAND gate with inputs A and B has an
output of 0 if:
a)
A is 0 b)
B is 0 c)
Both A and B is 0 d) Both A
and B is 1
34) Under similar conditions of the inputs, the
outputs of following pairs of gates are inverted:
a)
OR and NOR b) AND and
NAND c) XOR and XNOR d) All of above
35) XOR gate can be constructed by combining:
a)
OR, AND, NOT gates b) NOR, AND, NOT
gates c) OR, NOR, NOT gates d) OR, NAND, NOT
36) The bubble in the symbols of certain gates
indicates the operation of:
a)
Inversion b)
Addition c)
Compensation d) Both
(a) and (b)
37) In OR gate, the output is 1 if:
a)
At least one input is 1 b) Both
inputs are 0 c) Both
inputs are 1 d) Both (a)
and (b)
38) In describing functions of digital systems, 0
represents:
a)
Off bulb b)
True statement c)
Closed switch d) On
bulb
39) The value of LDR increases when light of falling
on it:
a)
Decreases b)
Increases c)
Remains constant d) May be
(a) or (b)
40) Output resistance of the op-amp is the
resistance b/w:
a)
Output terminal and (+) input b)
Output terminal and (-) input
c)
Output terminal and ground d)
Either (a) or (b)
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