EMI & AC - Alternating Current
Q. If the inductance of a coil is doubled, what happens to its inductive reactance at a constant frequency? (2022)
-
A.
It doubles
-
B.
It halves
-
C.
It remains the same
-
D.
It quadruples
Solution
Inductive reactance (X_L) is given by X_L = 2πfL. If the inductance (L) is doubled, X_L will also double.
Correct Answer: A — It doubles
Learn More →
Q. In a series RLC circuit, what happens at resonance? (2020)
-
A.
Impedance is minimum
-
B.
Current is minimum
-
C.
Voltage is maximum
-
D.
Power factor is zero
Solution
At resonance in a series RLC circuit, the impedance is minimum, and the circuit behaves like a purely resistive circuit.
Correct Answer: A — Impedance is minimum
Learn More →
Q. What is the average power consumed in an AC circuit with a power factor of 1? (2019)
-
A.
Zero
-
B.
RMS voltage
-
C.
RMS current
-
D.
Maximum power
Solution
When the power factor is 1, the average power consumed is maximum and is given by P = V_rms × I_rms.
Correct Answer: D — Maximum power
Learn More →
Q. What is the formula for calculating the impedance in an RLC series circuit? (2022)
-
A.
Z = R + jX
-
B.
Z = √(R^2 + X^2)
-
C.
Z = R + X
-
D.
Z = R - jX
Solution
The impedance (Z) in an RLC series circuit is calculated using the formula Z = √(R^2 + X^2), where X is the total reactance.
Correct Answer: B — Z = √(R^2 + X^2)
Learn More →
Q. What is the peak voltage of an AC source if its RMS voltage is 220 V? (2021)
-
A.
311 V
-
B.
220 V
-
C.
155 V
-
D.
440 V
Solution
The peak voltage (V_peak) is related to the RMS voltage (V_rms) by the formula V_peak = V_rms × √2. Therefore, V_peak = 220 V × √2 ≈ 311 V.
Correct Answer: A — 311 V
Learn More →
Q. What is the relationship between the RMS and average value of a sinusoidal AC current? (2023)
-
A.
RMS = Average
-
B.
RMS = Average × √2
-
C.
RMS = Average / √2
-
D.
RMS = Average × 2
Solution
For a sinusoidal AC current, the relationship is RMS = Average / √2.
Correct Answer: C — RMS = Average / √2
Learn More →
Showing 1 to 6 of 6 (1 Pages)
