A p-n-p transistor is used in common-emitter mode in an amplifier circuit. A change of 45 µA in the base current brings a change of 3 mA in collector current and 0.05 V in base-emitter voltage. If a load of 7 kΩ is used, then voltage gain of amplifier is

• 729.25

• 824.41

• 236.34

• 424.27

A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is

• 5 mA 

• 10 mA 

• 15 mA

• 20 mA

In the following circuit, the output Y becomes one for the inputs

• A= 0, B = 1, C = 0

• A = 1, B = 1, C = 0

• A =1, B= 1, C = 1

• A = 1, B= 0, C = 1

Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (E_g)_C , (E_g )_Si , and (E_g)_Ge  respectively. Which one of the following relationships is true in their case ?

• (E_g)_C > (E_g)_Si

• (E_g)_C = (E_g)_Si

• (E_g)_C < (E_g)_Ge

• (E_g)_C < (E_g)_Si

Then n-type semiconductors are obtained, when germanium is doped with

• arsenic

• phosphorus

• antimony

• any one of these

Which logic gate is represented by the following combination of logic gates ?

• OR

• NOR

• AND

• NAND

The depletion layer of a p-n junction

• is of constant width irrespective of the bias

• acts like an insulating zone under reverse bias

• has a width that increases with an increase in forward bias

• is depleted of ions

A Si and a Ge diode has identical physical dimensions. The band gap in Si is larger than that in Ge. An identical reverse bias is applied across the diodes

• The reverse current in Ge is larger than that in Si

• The reverse current in Si is larger than that in Ge

• The reverse current is identical in the two diodes

• The relative magnitude of the reverse currents cannot be determined from the given data only

A junction diode has a resistance of 25 Ω when forward biased and 2500 Ω when reverse biased. The current in the diode, for the arrangement shown will be

• $\frac{1}{15} \mathrm{A}$

• $\frac{1}{7} \mathrm{A}$

• $\frac{1}{25} \mathrm{A}$

• $\frac{1}{180}\mathrm{A}$

In a common emitter configuration, a transistor has β = 50 and input resistance 1 kΩ. If the peak value of AC input is 0.01 V, then the peak value of collector current is

• 0.01 µA

• 0.25 µA

• 100 µA

• 500 µA