Power in AC Circuits, Wattless Current NEET Questions

Physics - Electromagnetic Induction and Alternating Currents

Power in AC Circuits, Wattless Current MCQ Questions


7.
Average power dissipated in a pure capacitor in AC circuit is:
A.
V_rms × I_rms
B.
Zero
C.
I_rms²·X_C
D.
V_rms²/X_C
😑 View Answer Rough Work Error
ANSWER :
B. Zero
8.
If a resistor is connected to AC source v = V₀ sin(ωt), the instantaneous power is:
A.
p = V₀ sin(ωt)/R
B.
Constant
C.
p = V₀² cos²(ωt)/R
D.
p = V₀² sin²(ωt)/R
😑 View Answer Rough Work Error
ANSWER :
D. p = V₀² sin²(ωt)/R
9.
An AC voltage v = 100 sin(100πt) V is applied across a 10 Ω resistor. The average power dissipated is:
A.
1000 W
B.
100 W
C.
10000 W
D.
500 W
😑 View Answer Rough Work Error
ANSWER :
D. 500 W
10.
An AC source supplies V_rms = 220 V at 50 Hz to a circuit with impedance Z = 100 Ω and phase angle φ = 60°. Average power is:
A.
121 W
B.
484 W
C.
100 W
D.
242 W
😑 View Answer Rough Work Error
ANSWER :
D. 242 W
11.
The instantaneous power in an AC circuit can be:
A.
Always positive only
B.
Both positive (energy from source) and negative (energy to source)
C.
Only positive or zero
D.
Always equal to average power
😑 View Answer Rough Work Error
ANSWER :
B. Both positive (energy from source) and negative (energy to source)
12.
The average value of cos²(ωt) over a complete cycle is:
A.
1
B.
1/√2
C.
0
D.
1/2
😑 View Answer Rough Work Error
ANSWER :
D. 1/2