Notebook

Objective Questions on Basic Electronics- Semiconductor, Integrated Circuits, Logic Gates

Objective Questions ELECTRONICS

SEMI CONDUCTORS

SEMI CONDUCTORS ARE USED MAINLY IN

DIODE

TRANSISTOR

INTEGRATED CIRCUITS (IC)

GATES

LOGIC GATES ARE

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Q .A semiconductor has ………… temperature coefficient of resistance.

Positive
Zero
Negative.....
None of the above

Q A semiconductor is formed by ……… bonds.

Covalent.....
Electrovalent
Co-ordinate
None of the above

Q.The most commonly used semiconductor is ………..

Germanium
Silicon....
Carbon
Sulphur

Q. A semiconductor has generally ……………… valence electrons.

2
3
6
4....

Q. The resistivity of pure germanium under standard conditions is about ……….

6 x 104Ω cm
60Ω cm....
3 x 106Ω cm
6 x 10-4Ω cm

Q.The resistivity of a pure silicon is about ……………

100 Ω cm
6000 Ω cm.....
3 x 105 Ω m
6 x 10-8 Ω cm

Q. When a pure semiconductor is heated, its resistance …………..

Goes up
Goes down....
Remains the same
Can’t say

Q.When a pentavalent impurity is added to a pure semiconductor, it becomes ………

An insulator
An intrinsic semiconductor
p-type semiconductor
n-type semiconductor.....

Q. Addition of pentavalent impurity to a semiconductor creates many ……..

Free electrons....
Holes
Valence electrons
Bound electrons

Q. A pentavalent impurity has ………. Valence electrons

3
5....
4
6

Q. An n-type semiconductor is ………

Positively charged
Negatively charged
Electrically neutral...
None of the above

Q. A trivalent impurity has ….. valence electrons

4
5
6
3.....

Q. Addition of trivalent impurity to a semiconductor creates many ……..

Holes...
Free electrons
Valence electrons
Bound electrons

Q. A hole in a semiconductor is defined as …………….

A free electron
The incomplete part of an electron pair bond..
A free proton
A free neutron

Q. The impurity level in an extrinsic semiconductor is about ….. of pure semiconductor.

10 atoms for 108 atoms
1 atom for 108 atoms....
1 atom for 104 atoms
1 atom for 100 atoms

Q. As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor ………..

Remains the same
Increases
Decreases....
None of the above

Q.A hole and electron in close proximity would tend to ……….

Repel each other
Attract each other....
Have no effect on each other
None of the above

Q. In a semiconductor, current conduction is due to ……..

Only holes
Only free electrons
Holes and free electrons....
None of the above

Q. The random motion of holes and free electrons due to thermal agitation is called ……….

Diffusion....
Pressure
Ionisation
None of the above

Q. At room temperature, an intrinsic silicon crystal acts approximately as ……

A battery
A conductor
An insulator....
A piece of copper wire
Q. A forward biased pn junction diode has a resistance of the order of

Ω...
kΩ
MΩ
None of the above

Q. The battery connections required to forward bias a pn junction are ……

+ve terminal to p and –ve terminal to n...
-ve terminal to p and +ve terminal to n
-ve terminal to p and –ve terminal to n
None of the above

Q. The barrier voltage at a pn junction for germanium is about ………

5 V
3 V
Zero
0.3 V.....

Q. In the depletion region of a pn junction, there is a shortage of ……..

Acceptor ions
Holes and electrons....
Donor ions
None of the above

Q.A reverse bias pn junction has …………

Very narrow depletion layer
Almost no current....
Very low resistance
Large current flow

Q.A pn junction acts as a ……….

Controlled switch
Bidirectional switch
Unidirectional switch....
None of the above

Q. A reverse biased pn junction has resistance of the order of

Ω
kΩ
MΩ....
None of the above

Q. The leakage current across a pn junction is due to …………..

Minority carriers....
Majority carriers
Junction capacitance
None of the above

Q.When the temperature of an extrinsic semiconductor is increased, the pronounced effect is on……

Junction capacitance
Minority carriers....
Majority carriers
None of the above

Q. With forward bias to a pn junction , the width of depletion layer ………

Decreases....
Increases
Remains the same
None of the above

Q.  The leakage current in a pn junction is of the order of

Aa
mA
kA
µA....

Q. In an intrinsic semiconductor, the number of free electrons ………

Equals the number of holes....
Is greater than the number of holes
Is less than the number of holes
None of the above

Q. At room temperature, an intrinsic semiconductor has ……….

Many holes only
A few free electrons and holes....
Many free electrons only
No holes or free electrons

Q. At absolute temperature, an intrinsic semiconductor has ……….

A few free electrons
Many holes
Many free electrons
No holes or free electrons....

QThe strength of a semiconductor crystal comes from ……..

Forces between nuclei
Forces between protons
Electron-pair bonds.....
None of the above