Physics

This is a Multiple Choice Questions as classified in NCERT Exemplar 

Answer- a, c

Explanation- Here emitter-base junction is forward biased i.e., the positive pole of emitter base battery is connected to base and its negative pole to emitter. Also, the collector base junction is reverse biased, i.e., the positive pole of the collector base battery is connected to collector and negative pole to base.

Thus, electron move from emmiter to base and cross over from emitter to collector.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer- (a, c)

Explanation- when we apply temperature across semiconductor then electron will starts from lower energy to high energy level that is from valence band to conduction band. When electron goes from lower to higher then holes that is left behind they goes to lower energy levels.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer- c

Explanation- C=A.B and D=A'B

E= C+D = (A.B)+ (A'.B)

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer-b

Explanation- r1=5kohm and r2= 5kohm and both are in series

Then V-0.3 = [ (r1+r2)10³] $*$ [0.2 $*$ 10^-3]

 V-0.3= 2

V= 2.3V

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer- c

Explanation- due to forward biasing the diffusion current in the circuit is very high and resistance in the circuit is very low. Thus voltage across pn junction is very low but in case of reverse biasing diffusion current very small so resistance becomes very high . and that end making high voltage across pn junction.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer-b

Explanation -when a neutral entity is there it contains both equal number of elctron and holes. Also when electron emit from neutral entity then it leave behind a vacancy that is hole.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer- d

Explanation- as we know that Ev = E_o/ $\sqrt[]{2}$  so E₀= Ev $\sqrt[]{2}$ so net voltage is 220 $\sqrt[]{2}$ V

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer-b

Explanation- from the figure we can say that diode D1 is reverse biased and diode D2 is forward biased so current will flow from B to A.