BASIC ELECTRONICS QUESTION BANK

Objective type questions(1st chapter) 1 mark each

1. The cut-in voltage of silicon p-n diode is ………

A)0.7V B)0.6Mv c)1.2V D)1.2mV

2. The cut-in voltage of Ge p-n diode is about………

A)0.6V B)0.6Mv c)0.3V D)1.2mV

3. The region near junction consisting immobile ion without any charge carrier is called

…….

A)p region B)n region c)depletion region D)p-n region

4. Applying external DC voltage to a diode is called……

A)Forward biasing B)Reverse biasing c)biasing D)none

5. Average DC load current for half wave rectifier is given by ……….

A)Im/π B) 2Im/ π c)Im/2 D)Im

6. RMS value of load current for half wave rectifier is given by ……….

A)Im/π B) 2Im/ π c)Im/2 D)Im

7. The ripple factor for half wave rectifier is……….

A)200 B) 0.56 c)0.48 D)1.211

8. Average DC load current for full wave rectifier is given by ……….

A)Im/π B) 2Im/ π c)Im/2 D)Im

9. RMS value of load current for full wave rectifier is given by ……….

A)Im/π B) 2Im/ π c)Im/2 D)Im/√2

10. The ripple factor for full wave rectifier is……….

A)200 B) 0.56 c)0.48 D)1.211

11. The rectifier efficiency is 40.6% for ………..rectifier

A) half wave B)Full wave C) Bridge D) none

12. The rectifier efficiency is 81.2% for ………..rectifier

A) half wave B)Full wave C) Bridge D) none

13. The average o/p voltage of half wave rectifier with an input of 300sin314t is

………

A)100V B)95.49V C)90.49V D) 90.00V

1. Draw and explain the V-I characteristics of Si and Ge diodes 05

2. What is diffusion and depletion region capacitance of a diode? Explain it briefly. 03

3. Distinguish between ‘drift current’ and diffusion current in a PN device 05

4. Define DC load line for a diode and explain the DC load line for the circuit consisting of

supply voltage in series with resistance and diode.

06

5. Draw the VI-characteristics of semiconductor diode and explain it 05

6. Draw the ideal and practical VI-Characteristics of diode. 05

7. Define reverse recovery time in a diode. How is the reverse recovery time kept minimal 05

8. Explain the operation of a Half-wave rectifier with relevant output waveforms 05

8. The input to a half wave rectifier is given through a 10:1 transformer from a supply given

by 230 sin 314t V. if Rf = 50Ω and RL = 500 Ω determine

(a) DC load Voltage (d) Rectification efficiency

(b) RMS load Voltage (e) DC power delivered to load

(c) PIV across the diode (f) Frequency of O/P W/F

06

9. Explain how full-wave rectification is achieved using two diodes and centre-tap

transformer with a circuit diagram and output waveforms relevant waveforms

05

10. Draw a circuit of a bridge rectifier and show that ripple factor of bridge rectifier is 0.48 08

11. A full wave single-phase rectifier consists of two diodes each having internal resistance

of 500 Ω. The circuit feeds a pure resistive load of 2000Ω. The secondary voltage with

reference to centre tap is 280V calculate.

(a) Peak load current (c) Direct current in each diode

(b) DC load current (d) DC output power

(e) PIV across each diode. (f) RMS Load current

(g) RMS current through each diode (h) DC load voltage.

06

12. A full wave rectifier using two diodes is supplied from an AC supply given by 220 sin

314t V through a centre tapped transformer of turns ratio 10:1 the load resistance is 1000

Ω and the forward resistance is 20 Ω calculate.

(a) Average load voltage (c) PIV across each diode

(b)RMS load current (d) DC output power

(e) Frequency of output

06

13. In a full wave bridge rectifier, the transformer secondary voltage is 100 sinwt. The

forward resistance of each diode is 25 Ω and the load resistance is 950 Ω calculate.

(a) DC output voltage (d) PIV across non conducting diode.

(b) Ripple factor (e) Percentage regulation

(c) Efficiency of rectification (f) Peak diode current

(g) DC load current (h) DC current through each diode.

(i) RMS current through each diode.

06

14.. Explain the operation of a half-wave rectifier with capacitor filter with the help of a

circuit diagram and relevant waveforms.

06

15. A full wave rectifier consists of two diodes each having internal resistance of 500 Ω.

The circuit feeds a pure resistive load of 2000 Ω. The secondary voltage with reference

to centre tap is 280V calculate.

(a) Peak load current (c) Direct current in each diode

(b) DC load current (d) DC output power

(e) PIV across each diode. (f) RMS Load current

(g) RMS current through each diode (h) DC load voltage.

06

16. A full wave rectifier using two diodes is supplied from an AC supply given by 220 Sin

314t V through a centre tapped transformer of turns ratio 10:1 the load resistance is 1000

Ω and the forward resistance is 20 Ω calculate.

(a) Average load voltage (c) PIV across each diode

(b)RMS load current (d) DC output power

(e) Frequency of output

06

17. Show that a diode is capable of rectification. Draw the circuit of bridge rectifier.

Explain its working.

08

18. Explain the operation of a half-wave rectifier with capacitor filter with the help of a

circuit diagram

08

19. Define ripple factor. Find the ripple factor of a half-wave rectifier. 05

20. Draw the circuit diagram of full wave rectifier with capacitor filter circuit. explain the

circuit operation. And derive the expression for ripple factor.

06

21. Explain working of full-wave rectifier circuit give the expressions for (a) DC voltage (b)

ripple factor (c) PIV (d) Efficiency (e) RMS value of Voltage. What are its advantages

over half wave rectifier.

08

22. In a full wave bridge rectifier, the transformer secondary voltage is 100 sin wt. The

forward resistance of each diode is 25 Ω and the load resistance is 950 Ω calculate.

(a) DC output voltage (d) PIV across non conducting diode.

(b) Ripple factor (e) Percentage regulation

(c) Efficiency of rectification (f) Peak diode current

(g) DC load current (h) DC current through each diode.

(i) RMS current through each diode.

08

23. . Draw the circuit of a full wave bridge rectifier and show that ripple factor = 0.48 and

efficiency = 81%

05

24. Discuss the different types of junction breakdown that can occur in a reverse-biased

diode.

05

26. Explain how a zener diode can be used for maintain constant voltage across a load 05

27. Design a zener diode voltage regulator to meet the following requirements.

Unregulated dc input voltage :

Vi :13-17V

08

Load Current, IL = 10mA.

Regulated output voltage, V0 = 10V

Minimum zener current IZmin = 5mA

Maximum power dissipation in zener PZmax = 500mW.

28. A half wave rectifier with capacitor filter is supplying a resistive load of 1000 Ω. The

value of filter capacitor is 200µf. if the supply voltage to the rectifier is 200V at 50Hz

calculate

(a) Ripple factor (c) DC load Current

(b) DC output voltage (d) PIV across the diode

(e) RMS ripple output voltage.

06

29. A full-wave rectifier using two diodes supplies a load of 2K Ω. The ac voltage applied to

the diodes is 200-0-200V. if a capacitor of value 500µF is connected across the load,

find

(a) Ripple factor (c) Ripple voltage on capacitor

(b) DC output Voltage (d) DC load current.

06

30. Design a zener diode voltage regulator to meet the following specifications

DC input voltage Vi : 20V

DC output voltage V0: 10V

Load current Il : 20mA

Minimum zener current Izmin : 10mA

Maximum zener current Iz max : 100mA

06

31. A full-wave bridge rectifier supplies a load of 400Ω parallel with a capacitor of 500µf if

the ac supply voltage is 230 sin 314t V find

(a) Ripple Factor (b) DC load Current

06

32. Explain the terms line regulation and load regulation. 05

UNIT-II

1. Convert (3576)8 to hexadecimal 05

2. Convert (725.25)8 to its decimal and binary equivalent 05

3. Subtract (111001)2 from (101011)2 using 2’s complement method. 05

4. Solve: [0.7642]10 = [ ?]2 01

5. [AD6CB]16 = [?]8 01

6. [11011.1011]2 = [?]8 01

7. Subtract using 2’s complement , 66 – 64 01

8. [1011.11001]2 = [….] 10 01

9. Convert [0.6875]10 = [….]8 01

10. A72E]16 = […..]8 01

11. [95.5]10 = […..]16 01

12. Perform using 2’s complement 48 – 23 04

13. Convert (3575)8 to hexadecimal 05

14. Convert (725.25)8 to its decimal and binary equivalent 05

15. Subtract (111001)2 from (101011)2 using 2’s complement method. 05

16. Perform the following.

(i) (342.56)10 = (?)2 (ii)(AB)16 = (?)10 (iii) (8000)10 = (….)16

(iv) Subtract (1101)2 from (1010)2 using 2’s complement.

10

17. Convert the following hexadecimal number into decimal

(a) A3BH (b) 2F3H

04

18. Convert the following

(101010.101)2 = (….)10

01

19. (7034)8 = (?) 10 01

20. (2616)10 = (?)16. 01

21. (934)10 = (?)8 01

22. Subtract using 1’s complement 101000 from 0101111 using 1’s complement. 02

23. (11011)2 = (--------)8 01

24. The 2’s complement of 1100110 is 02

25. The binary of (A5)16 is …………… 01

26. Convert (10110011010)2 into octal, decimal and hexadecimal 03

27. Subtract using 2’s complement (15 – 7)10 04

28. Perform the following conversion form one base to another. 06

(249.75)10 = (….)16.

(101111010.111)2 = (….)8

(B2F8)16 = (…)10

(4144.375)10 = (…)2

29. Convert each decimal to binary (i) (11.125)10 (ii) (0.625)10 04

30. Convert the following hexadecimal umber into decimal.

(i) A3B (ii) 2F3

04

31. Implement XNOR using only NOR 04

32. Prove that

___________

AB + A + AB = 0

04

33. Realize the following using basic gates

_ _ _ _ _ _

Y = BC + AC +AB

Y = BA + A B

Y = AB + A+ )( CB

06

34 Explain how AND, OR and Not gates can be obtained using only NAND gates. 04

35.

Realize following expressions using NOR gates

_

Y = A(B + C)

04

36. Simplify the following Boolean expressions.

__ _

AB + AC + ABC(AB + C)

______________________

__________

A B + ABC + A ( B + A B )

06

36. Simplify

_ _ _ _ _ _ _ _ _

03

XYZ + XYZ +XY+XY.

37. Simplify using De-morgan’s theorem

_______

____

__

ABCD

03

38. List the properties of Boolean algebra with an example. 06

39. Simplify the following Boolean expression and realize using only NAND gates.

_ _ _ _ _ _ _ _

Y = ABC+ABC+AB+AC

_________________________

_ _ _ _ _

Y = (A + BC)(A + B + C) (A + B)

08

40. State and prove De-Morgan’s theorem. 04

41. Implement OR and AND using only NOR gates 04

43. Simplify the following Boolean expression.

_ _ _ _ _ _ _ __

YZ + WXZ + WXYZ + WYZ

________

__ _ _ _ _ _ _

(X + Y) [(X(Y + Z )] + XY + XZ

___ __

(X + Y) (XZ + Z) (Y + XZ)

06

44. Simplify and implement the following using Boolean expression using logic gates

Y = AB + A C+ BC

Y = (A + B +C ) ( A + B + C)

Y = C (B + C) (A + B + C).

06