Q1. In a series RLC circuit, what happens at resonance? (2020)
Solution:
At resonance in a series RLC circuit, the impedance is minimum, and the circuit behaves like a purely resistive circuit.
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Q2. If the voltage across a capacitor in an AC circuit is 100 V RMS, what is the peak voltage? (2022)
Solution:
The peak voltage (V_peak) is calculated as V_peak = V_rms × √2 = 100 V × √2 ≈ 141.42 V.
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Q3. What is the average power consumed in an AC circuit with a power factor of 0.5 and an RMS voltage of 100 V with a current of 5 A? (2020)
Solution:
Average power (P) is given by P = V_rms × I_rms × power factor. Thus, P = 100 V × 5 A × 0.5 = 250 W.
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Q4. In an AC circuit, what is the unit of reactance? (2019)
Solution:
Reactance is measured in Ohms, just like resistance.
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Q5. If the voltage across an inductor is 100 V and the current through it is 5 A, what is the inductive reactance? (2023)
Solution:
Inductive reactance (X_L) can be calculated using the formula V = I × X_L. Rearranging gives X_L = V/I = 100 V / 5 A = 20 Ω.
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Q6. If the frequency of an AC source is increased, what happens to the inductive reactance? (2019)
Solution:
Inductive reactance (X_L) is directly proportional to frequency (f). Therefore, if frequency increases, X_L decreases.
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Q7. If the inductance of a coil is doubled, what happens to its inductive reactance at a constant frequency? (2022)
Solution:
Inductive reactance (X_L) is given by X_L = 2πfL. If the inductance (L) is doubled, X_L will also double.
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Q8. What is the formula for calculating the average power in an AC circuit? (2023)
Solution:
The average power (P) in an AC circuit is given by P = VI cos(φ), where φ is the phase difference between voltage and current.
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Q9. What is the effect of increasing the capacitance in an AC circuit? (2019)
Solution:
Increasing the capacitance decreases the capacitive reactance (X_C = 1/(2πfC)), which can lead to an increase in current.
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Q10. The impedance of an RLC circuit is minimum when which condition is satisfied? (2022)
Solution:
The impedance (Z) of an RLC circuit is minimum when the inductive reactance (X_L) equals the capacitive reactance (X_C), which is the condition for resonance.
