set 9 MCQ Questions & Answers Detailed Explanation

Question : 1

When n-type semiconductor is heated

a) number of holes increases while that of electrons decreases

b) number of electrons and holes remain same

c) number of electrons increases while that of holes decreases

d) number of electrons and holes increases equally

Question : 2

In the circuits shown below the ammeter A reads 4 amp. and the voltmeter V reads 20 volts. The value of the resistance R is

a) slightly less than 5 ohms

b) exactly 5 ohms

c) slightly more than 5 ohms

d) None of these

Question : 3

Due to the earth's magnetic field, charged cosmic ray particles

a) can never reach the equator

b) require greater kinetic energy to reach the equator than the poles

c) require less kinetic energy to reach the equator than the poles

d) can never reach the poles

Question : 4

Nickel-Cadmium (Ni-Cd) battery is used in

a) Transistors

b) Calculator

c) Cordless electronic appliances

d) All of the above

Question : 5

In semiconductors, at room temperature

a) the valence band is partially empty and the conduction band is partially filled

b) the valence band is completely filled and the conduction band is partially filled

c) the conduction band is completely empty

d) the valence band is completely filled

Question : 6

Fluorescent tubes are fitted with a choke. The choke coil :

a) reduces current in the circuit

b) steps up the line voltage

c) steps-down the line voltage

d) chokes low frequency current