M.C.Q (1 Marks)

MCQ 11 Mark

The potential barrier in p-n diode is due to:

A
depletion of positive charges near the junction
B
accumulation of positive charges near the junction
C
depletion of negative charges near the junction,
✓
accumulation of positive and negative charges near the junction

Answer

Correct option: D.

accumulation of positive and negative charges near the junction

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MCQ 21 Mark

A reverse biased diode, is equivalent to:

✓
an off switch
B
an on switch
C
a low resistance
D
none of the above

Answer

Correct option: A.

an off switch

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MCQ 31 Mark

Current through a reverse biased p-n junction, increases abruptly at:

✓
Breakdown voltage
B
0.0 V
C
0.3V
D
0.7V

Answer

Correct option: A.

Breakdown voltage

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MCQ 41 Mark

The energy levels of holes are:

A
in the valence band
B
in the conduction band
✓
in the band gap but close to valence band
D
in the band gap but close to conduction band

Answer

Correct option: C.

in the band gap but close to valence band

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MCQ 51 Mark

Electric conduction through a semiconductor is due to:

A
Electrons
B
holes
C
none of these
✓
both electrons and holes

Answer

Correct option: D.

both electrons and holes

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MCQ 61 Mark

In the reverse biasing of a $p-n$ junction diode

A
the width of the depletion layer decreases.
✓
the width of the depletion layer increases.
C
the number of minority charge carriers increase.
D
the number of majority charge carriers increase.

Answer

Correct option: B.

the width of the depletion layer increases.

(b) the width of the depletion layer increases.

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MCQ 71 Mark

For an intrinsic semiconductor ( $n_h$ and $n_e$ are the number of holes per unit volume and number of electrons per unit volume respectively)

A

$n_h<n_e$
✓
$n_h=n_e$
C
$n_h=\frac{n_c}{2}$
D
$n_h>n_c$

Answer

Correct option: B.

$n_h=n_e$

(b) : For intrinsic semiconductors, $n_e=n_h$

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MCQ 81 Mark

When the conductivity of a semiconductor is only due to the breaking of the covalent bonds, the semiconductor is called

A
donor
✓
intrinsic
C
acceptor
D
extrinsic

Answer

Correct option: B.

intrinsic

(b) : In intrinsic semiconductors, conductivity is only due to breaking of the covalent bonds.

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MCQ 91 Mark

In semiconductors at room temperature,

A
the valence band is completely filled.
B
the conduction band is completely filled.
✓
the conduction band is partially filled and valence band is partially empty.
D
the valence band is completely filled and the conduction band is partially filled.

Answer

Correct option: C.

the conduction band is partially filled and valence band is partially empty.

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MCQ 101 Mark

An $n$-type and a $p$-type silicon semiconductor can be obtained by doping pure silicon with

A
indium and sodium respectively
B
boron and arsenic respectively
✓
arsenic and boron respectively
D
sodium and magnesium respectively.

Answer

Correct option: C.

arsenic and boron respectively

(c) : An n-type semiconductor has electrons as majority charge carriers. Thus for obtaining a $n$-type semiconductor silicon should be doped with electron rich donor elements of $V$ A group like answer.
Similarly, a p-type semiconductor has holes as majority charge carriers. Thus for obtaining a $p$-type semiconductor silicon should be doped with acceptor elements of group III A like boron.

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MCQ 111 Mark

In a forward bias arrangement of a $p-n$ junction diode, the

A
direction of conventional current is from $n$-region to $p$-region in the diode
B
p-region is connected negative terminal of the battery
C
$n$-region is connected to the positive terminal of battery
✓
p-region is connected to the positive terminal of battery.

Answer

Correct option: D.

p-region is connected to the positive terminal of battery.

(d) : In a forward bias arrangement of a $p-n$ junction diode, the $p$-region is connected to the positive terminal of battery while $n$-region is connected to the negative terminal of battery.

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MCQ 121 Mark

Assuming that the junction diode is ideal, the current in the arrangement shown in figure is

A
$30 mA$
B
$40 mA$
✓
$20 mA$
D
$10 mA$

Answer

Correct option: C.

$20 mA$

(c)

In the given circuit the junction diode is forward biased and offers zero resistance.
Current, $I=\frac{3 V -1 V }{100 \Omega}=0.02 A =20 mA$

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MCQ 131 Mark

In case of $p-n$ junction diode, the width of depletion region is

A
decreased with heavy doping
✓
increased by reverse biasing
C
decreased with light doping
D
increased by forward biasing.

Answer

Correct option: B.

increased by reverse biasing

(b) : In case of $p-n$ junction diode, the width of depletion region is increased by reverse biasing. The potential barrier becomes higher as the battery further raises the potential of the $n$-side.

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MCQ 141 Mark

With forward biased mode, the $p-n$ junction diode

A
is one in which width of depletion layer increases
B
is one in which potential barrier increases
✓
acts as closed switch
D
acts as open switch

Answer

Correct option: C.

acts as closed switch

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MCQ 151 Mark

Photodiode is a device

✓
which is always operated in reverse bias
B
which of always operated in forward bias
C
in which photo current is independent of intensity of incident radiation
D
which may be operated in forward or reverse bias.

Answer

Correct option: A.

which is always operated in reverse bias

(a) : Photodiode is a device which is always operated in reverse bias.

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MCQ 161 Mark

In insulators (C.B. is conduction band and V.B. is valence band)

A
V.B. is partially filled with electrons.
B
C.B. is partially filled with electrons.
✓
C.B. is empty and V.B. is filled with electrons.
D
C.B. is filled with electrons and V.B. is empty.

Answer

Correct option: C.

C.B. is empty and V.B. is filled with electrons.

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MCQ 171 Mark

For an ideal junction diode,

A
forward bias resistance is infinity.
B
forward bias resistance is zero.
C
reverse bias resistance is infinity.
✓
both (B) and (C).

Answer

Correct option: D.

both (B) and (C).

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MCQ 181 Mark

In the circuit shown below Di and D2 are two silicon diodes. The current in the circuit is …………….

A
$ 2 A$
B
$2 mA$
C
$0.8 mA$
✓
very small (approx 0)

Answer

Correct option: D.

very small (approx 0)

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MCQ 191 Mark

For p-n junction in reverse bias, which of the following is true?

✓
There is no current through P-N junction due to majority carriers from both regions.
B
Width of potential barriers is small and it offers low resistance.
C
Current is due to majority carriers.
D
Both (B) and (C )

Answer

Correct option: A.

There is no current through P-N junction due to majority carriers from both regions.

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MCQ 201 Mark

The width of depletion region ……………

✓
becomes small in forward bias of diode
B
becomes large in forward bias of diode
C
is not affected upon by the bias
D
becomes small in reverse bias of diode

Answer

Correct option: A.

becomes small in forward bias of diode

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MCQ 211 Mark

In an unbiased p-n junction, holes diffuse from the p-region to n-region because

A
free electrons in the n-region attract them.
B
they move across the junction by the potential difference.
✓
hole concentration in p-region is more as compared to n-region.
D
all the above.

Answer

Correct option: C.

hole concentration in p-region is more as compared to n-region.

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MCQ 221 Mark

If a p-n junction diode is not connected to any circuit, then

A
the potential is same everywhere.
B
potential is not same and n-type side has lower potential than p-type side.
C
there is an electric field at junction direction from p-type side to n-type side.
✓
there is an electric field at the junction directed from n-type side to p-type side.

Answer

Correct option: D.

there is an electric field at the junction directed from n-type side to p-type side.

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MCQ 231 Mark

The drift current in a p-n junction is

A
from the p region to n region.
✓
from the n region to p region.
C
from n to p region if the junction is forward biased and from p to n region if the junction is reverse biased.
D
from p to n region if the junction is forward biased and from n to p region if the junction is reverse biased.

Answer

Correct option: B.

from the n region to p region.

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MCQ 241 Mark

The movement of a hole is brought about by the valency being filled by a ………………..

A
free electrons
✓
valence electrons
C
positive ions
D
negative ions

Answer

Correct option: B.

valence electrons

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MCQ 251 Mark

The number of bonds formed in p-type and n-type semiconductors are respectively

A
4,5
✓
3,4
C
4,3
D
5,4

Answer

Correct option: B.

3,4

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MCQ 261 Mark

When a hole is produced in P-type semiconductor, there is ……………….

A
extra electron in valence band.
B
extra electron in conduction band.
✓
missing electron in valence band.
D
missing electron in conduction band.

Answer

Correct option: C.

missing electron in valence band.

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MCQ 271 Mark

What are majority carriers in a semiconductor?

A
Holes in n-type and electrons in p-type.
B
Holes in n-type and p-type both.
C
Electrons in n-type and p-type both.
✓
Holes in p-type and electrons in n-type.

Answer

Correct option: D.

Holes in p-type and electrons in n-type.

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MCQ 281 Mark

In a semiconductor, acceptor impurity is

A
antimony
✓
indium
C
phosphorous
D
arsenic

Answer

Correct option: B.

indium

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MCQ 291 Mark

For an extrinsic semiconductor, the valency of the donor impurity is …………..

A
2
B
1
C
4
✓
5

Answer

Correct option: D.

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MCQ 301 Mark

A pure semiconductor is ……………..

A
an extrinsic semiconductor
✓
an intrinsic semiconductor
C
p-type semiconductor
D
n-type semiconductor

Answer

Correct option: B.

an intrinsic semiconductor

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MCQ 311 Mark

In the crystal of pure Ge or Si, each covalent bond consists of …………..

A
1 electron
B
2 electron
C
3 electrons
D
4 electrons

Answer

2 electrons

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MCQ 321 Mark

In conduction band of solid, there is no electron at room temperature. The solid is ……………………..

A
semiconductors
✓
insulator
C
conductor
D
metal

Answer

Correct option: B.

insulator

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MCQ 331 Mark

When N-type semiconductor is heated, the ……………..

A
number of electrons and holes remains same.
B
number of electrons increases while that of holes decreases.
C
number of electrons decreases while that of holes increases.
✓
number of electrons and holes increases equally.

Answer

Correct option: D.

number of electrons and holes increases equally.

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MCQ 341 Mark

If the temperature of semiconductor is increased, the number of electrons in the valence band will ……………….

✓
decrease
B
remains same
C
increase
D
either increase or decrease

Answer

Correct option: A.

decrease

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MCQ 351 Mark

The number of electrons in the valence shell of semiconductor is ……………

A
less than 4
✓
equal to 4
C
more than 4
D
zero

Answer

Correct option: B.

equal to 4

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Physics M.C.Q (1 Marks)

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