Alternating Current - Online Test
Q1. Reactance of a 3.00-H inductor at a frequency of 80.0 Hz is
Answer : Option D
Explaination / Solution:
L = 3 H
f = 80 Hz
Inductive reactance
Q2. Inductance of an inductor whose reactance is 120 Ω at 80.0 Hz is
Answer : Option A
Explaination / Solution:
XL=120Ωf=80HzXL=ωL=2πfLL=XL2πf=1202×3.14×80=0.239H
Q3. Domestic power supply in India is
Answer : Option B
Explaination / Solution:
India use ac power supply of frequency 50 Hz and voltage 230V while America uses ac supply of frequency 60Hz and voltage 110V.
Q4. In an L-R-C series circuit, the rms voltage across the resistor is 30.0 V, across the capacitor it is 90.0 V, and across the inductor it is 50.0 V. Rms voltage of the source is
Answer : Option A
Explaination / Solution:
VR=30V
VC=90V
VL=50V
V=(VC−VL)2+VR2−−−−−−−−−−−−−−√=(90−50)2+302−−−−−−−−−−−−−√=402+302−−−−−−−−√V=50volt
Q5. An L-R-C series circuit has phase angle .The voltage amplitude of the source is 90.0 V. Voltage amplitude across the resistor is
Answer : Option A
Explaination / Solution:
in L-R-C circuit phaser diagram
hence,
Q6. You have a 200.0 Ω resistor, a 0.400-H inductor, 5.0 μF a capacitor, and a variable frequency ac source with an amplitude of 3.00 V. You connect all four elements together to form a series circuit. Current amplitude at an angular frequency of 400 rad/s is
Answer : Option C
Explaination / Solution:
No Explaination.
Q7. A coil has a resistance of 48.0 . At a frequency of 80.0 Hz the voltage across the coil leads the current in it by . Inductance of the coil is
Answer : Option C
Explaination / Solution:
in series LR circuit
tanϕ=ωLRL=0.124H
