The PN junction diode is used as

(1) An amplifier                       

(2) A rectifier

(3) An oscillator                       

(4) A modulator

In the depletion region of an unbiased P-N junction diode there are

(1) Only electrons

(2) Only holes

(3) Both electrons and holes

(4) Only fixed ions

On increasing the reverse bias to a large value in a PN-junction diode, current

1. Increases slowly                 

2. Remains fixed

3. Suddenly increases             

4. Decreases slowly

In the case of forward biasing of PN-junction, which one of the following figures correctly depicts the direction of flow of carriers

A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be

(1) A P-type semiconductor               

(2) An N-type semiconductor

(3) A PN-junction                               

(4) An intrinsic semiconductor

The approximate ratio of resistances in the forward and reverse bias of the P-N junction diode is:

(a) ${10}^2:1$                     (b) ${10}^{-2}:1$
(c) $1:{10}^{-4}$                   (d) $1:{10}^4$ 

In a junction diode, the holes are due to

(1) Protons                               

(2) Neutrons

(3) Extra electrons                     

(4) Missing of electrons

In forward bias, the width of potential barrier in a P-N junction diode 

(1) Increases

(2) Decreases

(3) Remains constant

(4) First increases then decreases

The cause of the potential barrier in a P-N diode is

(1) Depletion of positive charges near the junction

(2) Concentration of positive charges near the junction

(3) Depletion of negative charges near the junction

(4) Concentration of positive and negative charges near the junction