Practice Questions on Diode with Answers.

Q1. if Vp is the sinusoidal peak voltage in the secondary of the transformer, the average d.c. output voltage of half wave rectifier is

(a) Vp/2
(b) 2Vp/3.14
(C) Vp/3.14
(d) 3.14 Vp

Q2. When a P-N junction is formed what happens in the P and N regions ?

(a) The top of valence bands are aligned
(6) The bottom of conduction bands are aligned
(c) The majority carrier concentration are equalized
(d) The Fermi levels are aligned

Q3. On forward biasing of a P-N junction diode the depletion width

(a) decreases
(b) increases
(c) remains unchanged
(d) increases in the begining, then becomes constant

Q4. If we apply a voltage V = Vpsinωt at the input of a half-wave rectifer, then the output DC voltage is

(a) Vp/π
(b) 2Vp/π
(c) Vp/π
(d) Vp/2π

Q5. If logical 0 is 0 volt and logical 1 is +1 volt, the circuit  is a logic circuit commonly known as

(a) an OR gate
(b) an AND gate
(d) a flip-flop

Q6. Zener diode can be used as

(a) an amplifier
(b) an oscillator
(c) voltage regulator
(d) all of these

Q7. The peak value of the AC voltage across the secondary of the transformer in a half-wave rectifier without fitler is 9√2 volts. The maximum de voltage across the load will be about

(a) 9V
(b) 4V
(c) 6V
(d) 3.2V

Q8. The dominant mechanisms for the motion of charge cariers in forward biased and reverse biased P-N junctions are

(a) drift in forward bias , diffusion in reverse bias
(b) diffusion in forward bias , drift in reverse bias
(c) diffusion in both forward and everse bias
(d) drift in both forward and reverse biasAnswer

Q9. In a full-wave rectifier circuit using center tap transformer the dc voltage across the load is 16.48 volts, then the peak inverse voltage of each diode is

(a) 25.9 V
(b) 51.8 V
(c) 29.5 V
(d) 58.1 V

Q10. A multistage amplifier consists of three stages. The voltage gains of the stages are 30, 50 and 80 respectively. The overall voltage gain in dB will be

(a) 101.58
(b) 50.79
(c) 33.98
(d) 38.06

Q11. The dynamic resistance of an ideal p-n junction with forward current of 10 mA at room temperature is:

(d) 4.0 Ohm
(a) 2.5 Ohm
(6) 0.4 Ohm
(c) 0.25 Ohm

Q12. When a reverse voltage increases from 5V to 10V in a semiconductor diode, the depletion layer:

(a) becomes smaller
(b) becomes larger
(b) becomes unaffècted
(d) breakdown

Q13. The breakdown does not destroya zener diode provided the zener current is less than the

(a) breakdown voltage
(b) zener test current
(c) maximum zener current rating
(d) barrier potential

Q14. The rms value of full wave rectified waveform is :

(a) 0.636 times the peak value
(b) 0.707 times the peak value
(c) 0.5 times the peak value
(d) 0.373 times the peak value

Q15. The value of the ideality factor η in the diode equation for current flowing in P-N junction made from Si is

(a) η = 1 for all currents
(b) η = 2 for all currents
(c) η = 1 for small current but η = 2 for large current
(d) η = 2 for small current but η = 1 for large current

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