250+ TOP MCQs on Electronic Devices and Circuits Basic Concepts and Answers

Electronic Devices and Circuits Multiple Choice Questions on “Basic Concepts”.

1. A solid copper sphere, 10 cm in diameter is deprived of 1020 electrons by a charging scheme. The charge on the sphere is _________
A. 160.2 C
B. -160.2 C
C. 16.02 C
D. -16.02 C

Answer: C
Clarification: n 1020, Q = ne = e 1020 = 16.02 C.
Charge on sphere will be positive.

2. A lightning bolt carrying 15,000 A lasts for 100 s. If the lightning strikes an airplane flying at 2 km, the charge deposited on the plane is _________
A. 13.33 C
B. 75 C
C. 1500 C
D. 1.5 C

Answer: D
Clarification: dQ = i dt = 15000 x 100µ = 1.5 C.

3. If 120 C of charge passes through an electric conductor in 60 seC. the current in the conductor is _________
A. 0.5 A
B. 2 A
C. 3.33 mA
D. 0.3 mA

Answer: B
Clarification: i = dQ/dt = 120/60 = 2A.

4. The energy required to move 120 coulomb through 3 V is _________
A. 25 mJ
B. 360 J
C. 40 J
D. 2.78 mJ

Answer: B
Clarification: W = Qv = 360 J.

5. Consider the circuit graph shown in figure below. Each branch of circuit graph represent a circuit element. The value of voltage V1 is:
A. 30 V
B. 25 V
C. 20 V
D. 15 V

Answer: D
Clarification: 100 = 65 + V2 => V2 = 35 V
V3 – 30 = V2 => V3 = 65 V
105 – V3 + V4 – 65 = 0 => V4 = 25 V
V4 + 15 – 55 + V1 = 0 => V1 = 15 V.

6. What will be the value of Req in the following Circuit?
A. 11.86 ohm
B. 10 ohm
C. 25 ohm
D. 11.18 ohm

Answer: D

7. In the circuit the dependent source __________
A. supplies 16 W
B. absorbs 16 W
C. supplies 32 W
D. absorbs 32 W

Answer: D
Clarification: P = VIx = 2Ix Ix = 2 x 16 or 32 watt (absorB..

8. Twelve 6 ohm resistors are used to form an edge of a cube. The resistance between two diagonally opposite corner of the cube (in ohm) is ________
A. 5/6
B. 6/5
C. 5
D. 6

Answer: C

9. The energy required to charge a 10 µF capacitor to 100 V is ________
A. 0.1 J
B. 0.05 J
C. 5 x 10(-9) J
D. 10 x 10(-9) J

Answer: B
Clarification: Energy provided is equal to 0.5 CVxV.

10. A capacitor is charged by a constant current of 2 mA and results in a voltage increase of 12 V in a 10 sec interval. The value of capacitance is ________
A. 0.75 mF
B. 1.33 mF
C. 0.6 mF
D. 1.67 mF

Answer: D
Clarification: The capacitor current is given as i=C*(dv/dt), where dv/dt is the derivative of voltage, dt=t2-t1 given as 10 sec and dv is the change in voltage which is given as 12V.
So, we have C=i/(dv/dt)
=> C = 2mA/(12/10) = 2mA/(1.2).
Hence C = 1.67mF.