This set of Basic Electrical Engineering Problems focuses on “Alternating Current in a Capacitive Circuit”.
1. What is the resonance frequency of ac circuit?
a) 1/√LC
b) √(L/C)
c) √LC
d) LC
View Answer
Explanation: At resonance, XL=XC
ωL=1/ωC
ω=1/√LC.
2. What is impedance at resonance?
a) maximum
b) minimum
c) zero
d) cannot be determined
View Answer
Explanation: At resonance, XL=XC
Z2=R2+(XL-XC)2
Z=R So Z is minimum at resonance.
3. What is the value of impedance at resonance?
a) XL
b) XC
c) R
d) 0
View Answer
Explanation: At resonance, XL=XC
Z2=R2+(XL-XC)2
Z=R So Z is minimum at resonance.
4. What is φ in terms of voltage?
a) φ=cos-1V/VR
b) φ=cos-1V*VR
c) φ=cos-1VR/V
d) φ=tan-1V/VR
View Answer
Explanation: Form the voltage triangle, we get cosφ= VR/V.
Hence φ=cos-1VR/V.
5. What is tanϕ for RC circuit?
a) XC/R
b) XL/R
c) R/Z
d) Z/R
View Answer
Explanation: From the impedance triangle, height gives capacitive reactance and base gives resistance.
tanϕ=XC/R.
6. What is the resonance condition?
a) When XL>XC
b) When XL<XC
c) When XL=XC
d) When XC=infinity
View Answer
Explanation: The current is in phase with the voltage when the capacitive reactance is in equal to the inductive reactance. This is known as resonance condition.
7. What is the frequency in resonance condition?
a) Minimum
b) Maximum
c) Cannot be determined
d) Zero
View Answer
Explanation: At resonance condition, the frequency is maximum since the inductive reactance is equal to the capacitive reactance. XL=XC.
Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.
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