A series LCR circuit is connected to a 45 sin(ωt) Volt source. The resonant angular frequency of the circuit is 105 rad s−1 and current amplitude at resonance is I0. When the angular frequency of the source is ω = 8 × 104 rad s−1, the current amplitude in the circuit is 0.05 I0. If L = 50 mH, match each entry in List-I with an appropriate value from List-II and choose the correct option.
| List-I | List-II |
|---|---|
| (P) | (1) |
| (Q) | (2) |
| (R) | (3) |
| (S) | (4) |
| (5) |
Correct Answer :
P → 3, Q → 1, R → 4, S → 2
Solution :
The correct option is P → 3, Q → 1, R → 4, S → 2.
Given Data:
Peak Voltage of the AC source, V0 = 45 V
Resonant angular frequency, ω0 = 105 rad s−1
Inductance, L = 50 mH = 50 × 10−3 H = 0.05 H
At angular frequency ω = 8 × 104 rad s−1, current amplitude I = 0.05 I0
Step-by-step Derivation:
1. Finding the Net Reactance at ω = 8 × 104 rad s−1:
The inductive reactance is XL = ωL and capacitive reactance is XC = 1/(ωC).
Since ω02 = 1/(LC), we have 1/C = ω02L.
Substituting 1/C in the net reactance X:
Plugging in the given values:
2. Determining Resistance R and Current Amplitude at Resonance I0 (P):
The current amplitude at frequency ω is given by:
At resonance, I0 = V0 / R. Given I = 0.05 I0:
Now, calculate peak current I0:
Thus, (P) → (3).
3. Calculating Quality Factor Q (Q):
The Quality factor of the circuit is given by:
Thus, (Q) → (1).
4. Calculating Bandwidth (R):
Bandwidth (Δω) is given by:
Thus, (R) → (4).
5. Calculating Peak Power Dissipated at Resonance (S):
At resonance, maximum/peak power dissipated is:
Thus, (S) → (2).
Conclusion:
Matching the entries:
P → 3
Q → 1
R → 4
S → 2
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