A. φ = cos-1V/VR
B. φ = cos-1V × VR
C. φ = cos-1VR/V
D. φ = tan-1V/VR
Answer: C
From the voltage triangle, we get
cosφ = VR/V.
Hence φ = cos-1VR/V.
22. What is tanϕ for the RC circuit?
A. XC/R
B. XL/R
C. R/Z
D. Z/R
Answer: A
From the impedance triangle, height gives capacitive reactance, and base gives resistance.
tanϕ = XC/R.
23. What is the resonance condition?
A. When XL>XC
B. When XL<xC C. When XL = XC
D. When XC = infinity
Answer: C
The current is in phase with the voltage when the capacitive reactance is in equal to the inductive reactance. This is known as the resonance condition.
24. What is the frequency in the resonance condition?
A. Minimum
B. Maximum
C. Cannot be determined
D. Zero
Answer: B
At the resonance condition, the frequency is maximum since the inductive reactance is equal to the capacitive reactance. XL = XC.
25. Can the capacitor fully charge using alternating current?
A. yes
B. no
C. may or may not
D. depend on the value of capacitance
Answer: A
No, the capacitor cannot be fully charged using alternating current because as soon as the capacitor charges, the alternating current reverses its polarity thereby discharging it.
26. What is the resistance offered by a capacitor?
A. Susceptance
B. Conductance
C. Admittance
D. Reactance
Answer: D
The resistance offered to alternating current by an inductor or capacitor is known as reactance which is equivalent to the resistance of the resistor.
27. The combination of resistance and reactance known as ___________
A. Susceptance
B. Impedance
C. Conductance
D. Admittance
Answer: B
The combination of resistance and reactance is known as impedance. It is the equivalent resistance of an RLC alternating circuit.
28. What is the relation between reactance, resistance, and impedance?
A. Z = R+jX
B. Z = R+X
C. Z = R-X
D. Z = R-jX
Answer: A
The combination of resistance and reactance is known as impedance.
Z = R+jX
Where
Z is impedance
R is resistance and X is reactance.
29. What is the real part of the impedance of the RLC circuit?
A. Resistance
B. Conductance
C. Admittance
D. Reactance
Answer: A
The combination of resistance and reactance is known as impedance.
Z = R+jX
where
Z is impedance
R is resistance
X is reactance.
R is a real part of Z.
30. What is the imaginary part of the impedance of the RLC circuit?
A. Resistance
B. Conductance
C. Admittance
D. Reactance
Answer: D
The combination of resistance and reactance is known as impedance.
