This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Resistance and Capacitance in Series”.

1. If in an alternating current circuit, resistance is 5 ohm, capacitive reactance is 12 ohm, what is the impedance?

a) 5 ohm

b) 10 ohm

c) 12 ohm

d) 13 ohm

View Answer

Explanation: R=5Ω, X

_{C}=12Ω

Z

^{2}=R

^{2}+X

_{C}

^{2}Substituting the values we get,

Z

^{2}= 5

^{2}+ 12

^{2}

Z

^{2}= 169

Z=13 Ω.

2. If in an alternating current circuit, impedance is 26 ohm, capacitive reactance is 24 ohm, what is the resistance?

a) 25 ohm

b) 10 ohm

c) 12 ohm

d) 23 ohm

View Answer

Explanation: Z=26Ω, X

_{C}=24Ω

Z

^{2}=R

^{2}+X

_{C}

^{2}Substituting the values we get,

26

^{2}= R

^{2}+ 24

^{2}

676 = R

^{2}+ 576

R

^{2}= 100

R=10 Ω.

3. If in an alternating current circuit, capacitance of 30 µF is connected to a supply of 200V,50Hz. Find the current in the circuit.

a) 1.38 A

b) 1.89 A

c) 1.74 A

d) 0.89 A

View Answer

Explanation: X

_{C}=1/(2πfC)=106.1

I=V/X

_{C}=200/106.1=1.89 A.

4. If in an alternating current circuit, capacitance C is connected to a supply of 200V,50Hz. Current in the circuit is 1.89 A. Find the capacitance C.

a) 30 µF

b) 20 µF

c) 10 µF

d) 15 µF

View Answer

Explanation: X

_{C}= V/I = 200/1.89 = 106.1 Ω. X

_{C}=1/(2πfC) Substituting the values we get C = 30 µF.

5. In ac circuit, resistance 5 ohm is connected with capacitor having capacitive reactance 12 ohm. Supply of 260 V is connected to the circuit. Calculate the current in the circuit.

a) 40 A

b) 10 A

c) 20 A

d) 30 A

View Answer

Explanation: Z

^{2}=R

^{2}+X

_{C}

^{2}Substituting the values we get Z

^{2}= 5

^{2}+ 12

^{2}

Z

^{2}= 169

Z=13 Ω.

I=V/Z = 260/13=20 A.

6. In ac circuit, resistance 5 ohm is connected with capacitor having capacitive reactance 12 ohm. Supply of 260 V is connected to the circuit. Calculate the voltage across resistance.

a) 300 V

b) 200 V

c) 240 V

d) 100 V

View Answer

Explanation: Z

^{2}=R

^{2}+X

_{C}

^{2}Substituting the values we get

Z

^{2}= 5

^{2}+ 12

^{2}

Z

^{2}= 169

Z=13 Ω.

I = V/Z = 260/13=20 A.

V

_{R}=iR=20*5=100 V.

7. In ac circuit, resistance 5 ohm is connected with a capacitor having capacitive reactance 12 ohm. Supply of 260 V is connected to the circuit. Calculate the voltage across a capacitor.

a) 300 V

b) 200 V

c) 240 V

d) 100 V

View Answer

Explanation: Z

^{2}=R

^{2}+X

_{C}

^{2}Substituting the values we get

Z

^{2}= 5

^{2}+ 12

^{2}

Z

^{2}= 169

Z=13 Ω.

I = V/Z = 260/13=20 A.

V

_{C}=iX

_{C}=20*12=240 V.

**Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.**

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