Electronic Devices And Circuits - Study Mode

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[#126] Effectively, how many valence electrons are there in each atom within a silicon crystal?

(A) 2

(B) 4

(C) 8

(D) 16

Correct Answer

(B) 4

[#127] Which of the following are essentials of a transistor biasing circuit? 1. Proper zero signal collector current flow 2. V CE should not fall below 0.5 V for Germanium and 1 V for Silicon 3. Ensure stabilization of operating point 4. Loading to the source

(A) 1, 2 and 3 only

(B) 1, 2 and 4 only

(C) 3 and 4 only

(D) 1, 2, 3 and 4

Correct Answer

(A) 1, 2 and 3 only

[#128] Which one of the following is the exact expression for I CEO (i.e. collector to emitter current with base open) in a junction transistor? (Where I CBO is the collector to base current with emitter open, and α is the common base current gain)

(A) $$alpha .{{ ext{I}}_{{ ext{CBO}}}}$$

(B) $$frac{alpha }{{1 - alpha }}.{{ ext{I}}_{{ ext{CBO}}}}$$

(C) $$frac{{{{ ext{I}}_{{ ext{CBO}}}}}}{{1 - alpha }}$$

(D) $$left( {1 - alpha } ight){{ ext{I}}_{{ ext{CBO}}}}$$

Correct Answer

(C) $$frac{{{{ ext{I}}_{{ ext{CBO}}}}}}{{1 - alpha }}$$

[#129] The light output of LED varies as (Current) n , the value of n is about

(A) 0.5

(B) 1

(C) 1.3

(D) 2.1

Correct Answer

(C) 1.3

[#130] Which one of the following expressions may be used to correctly describe the temperature (T) variation of the intrinsic carrier density (n i ) of a semiconductor? E g is the band gap, A is pre-factor's k is Boltzmann constant.

(A) n i (T) = (A/T) exp (-E g /kT 2 )

(B) n i (T) = A(E g /kT) 10

(C) n i (T) = A exp(-E g /2kT)

(D) n i (T) = AT 3/2 exp(-E g /2kT)

Correct Answer

(D) n i (T) = AT 3/2 exp(-E g /2kT)