Zener breakdown takes place if 

(1) Doped impurity is low             

(2) Doped impurity is high

(3) Less impurity in N-part           

(4) Less impurity in P-type

The correct symbol for zener diode is:

1.		2.
3.		4.

Which one of the following statements is not correct

(1) A diode does not obey Ohm's law

(2) A PN junction diode symbol shows an arrow identifying the direction of current (forward) flow

(3) An ideal diode is an open switch

(4) An ideal diode is an ideal one way conductor

A semiconductor X is made by doping a germanium crystal with arsenic (Z = 33). A second semiconductor Y is made by doping germanium with indium (Z = 49). The two are joined end to end and connected to a battery as shown. Which of the following statements is correct

(1) X is P-type, Y is N-type and the junction is forward biased

(2) X is N-type, Y is P-type and the junction is forward biased

(3) X is P-type, Y is N-type and the junction is reverse biased

(4) X is N-type, Y is P-type and the junction is reverse biased

Which is the wrong statement in following sentences?

A device in which P and N-type semiconductors are used is more useful then a vacuum type because 

(1) Power is not necessary to heat the filament

(2) It is more stable

(3) Very less heat is produced in it

(4) Its efficiency is high due to a high voltage across the junction

In the diagram, the input is across terminals A and C and the output is across terminals B and D, then the output is:

(1) Zero                                                              

(2) Same as input

(3) Full wave rectifier  

(4) Half wave rectifier

The current through an ideal PN-junction shown in the following circuit diagram will be

(1) Zero

(2) 1 mA

(3) 10 mA

(4) 30 mA

If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be

(1) 50 Hz                           

(2) 70.7 Hz

(3) 100 Hz                         

(4) 25 Hz

A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with resistance of 20 $\mathrm{\Omega }$ across source. If 0.1 A passes through resistance then what is the voltage of the source

1. 1.5 V                     

2. 2.0 V

3. 2.5 V                     

4. 5 V

When NPN transistor is used as an amplifier

(1) Electrons move from base to collector

(2) Holes move from emitter to base

(3) Electrons move from collector to base

(4) Holes move from collector to emitter