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

1. In an RC series circuit ________

a) Applied voltage lags capacitor voltage

b) Applied voltage leads capacitor voltage

c) Current and voltage are in phase

d) Applied voltage and capacitive voltage are in phase

View Answer

Explanation: In an RC circuit, the applied voltage leads the current in the circuit, hence the applied voltage leads the capacitive voltage.

2. Which, among the following is the correct expression for φ?

a) φ=tan^{-1}(Xc/R)

b) φ=tan^{-1} (R/Xc)

c) φ=tan^{-1} (Xc*R)

d) φ=cos^{-1} (Xc/R)

View Answer

Explanation: Form the impedance triangle, we get tanφ= Xc/R.

Hence φ=tan

^{-1}(Xc/R).

3. For an RC circuit, the phase angle is always ________

a) Positive

b) Negative

c) 0

d) 90

View Answer

Explanation: For a series resistance and capacitance circuit, the phase angle is always a positive value because the current will always lead the voltage.

4. An RC network is one which consists of?

a) Resistor and capacitor in parallel

b) Resistor and capacitor in series

c) Resistor and inductor in parallel

d) Resistor and inductor in series

View Answer

Explanation: An R-C network is a network which consists of a resistor which is connected in series to a capacitor.

5. At DC, the capacitor acts as?

a) Open circuit

b) Short circuit

c) Resistor

d) Inductor

View Answer

Explanation: At DC, the inductor acts as a short circuit because the capacitive resistance is infinity. The frequency of a DC circuit is 0. The capacitive resistance=1/(2*pi*f*C). Therefore, if the frequency is 0, the capacitive resistance is infinity and it acts as an open circuit.

6. The expression for current in an RC circuit is?

a) i=(V/R)e^{(t/RC)}

b) i=(V/R)e^{(-t/RC)}

c) i=(V/R)/e^{(t/RC)}

d) i=(V/R)/e^{(-t/RC)}

View Answer

Explanation: The particular solution of the current equation is zero. Hence, the expression for the current in an RC circuit is:

i=(V/R)e

^{(-t/RC)}.

7. At DC, inductor acts as ___________

a) Open circuit

b) Short circuit

c) Resistor

d) Inductor

View Answer

Explanation: At DC, the inductor acts as a short circuit because the inductive resistance is zero. The frequency of a DC circuit is 0. The inductive resistance=(2*pi*f*L). Therefore, if the frequency is 0, the inductive resistance is zero and it acts as a short circuit.

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

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