Easy INTEGER +4 / -1 PYQ · JEE Mains 2025

An inductor of reactance $100 \Omega$, a capacitor of reactance $50 \Omega$, and a resistor of resistance $50 \Omega$ are connected in series with an AC source of $10 \mathrm{~V}, 50 \mathrm{~Hz}$. Average power dissipated by the circuit is ___________ W.

Answer (integer) 1

Solution

<p>To calculate the average power dissipated in the circuit, we follow these steps:</p> <p><p><strong>Formula for Power</strong>:</p> <p>$ P = V_{\text{rms}} \times I_{\text{rms}} \times \cos \phi $</p></p> <p><p><strong>Expressing Power in Terms of Voltage and Impedance</strong>:</p> <p>$ P = V_{\text{rms}} \times \frac{V_{\text{rms}}}{Z} \times \frac{R}{Z} $</p></p> <p><p><strong>Simplifying the Expression</strong>:</p> <p>$ P = \frac{V_{\text{rms}}^2 \times R}{Z^2} $</p></p> <p><p><strong>Calculate Impedance (Z)</strong>:</p> <p>The impedance of the circuit (Z) is calculated as:</p> <p>$ Z = \sqrt{R^2 + (X_L - X_C)^2} $</p> <p>Given:</p> <p>- $ X_L = 100 \, \Omega $</p> <p>- $ X_C = 50 \, \Omega $</p> <p>- $ R = 50 \, \Omega $</p> <p>$ X_L - X_C = 100 \, \Omega - 50 \, \Omega = 50 \, \Omega $</p> <p>Thus:</p> <p>$ Z = \sqrt{50^2 + 50^2} = 50\sqrt{2} \, \Omega $</p></p> <p><p><strong>Substitute Values to Find Power (P)</strong>:</p> <p>Given $ V_{\text{rms}} = 10 \, \text{V} $, we calculate $ P $ as follows:</p> <p>$ P = \frac{10^2 \times 50}{(50\sqrt{2})^2} $</p> <p>Simplifying further:</p> <p>$ P = \frac{100 \times 50}{2500 \times 2} = 1 \, \text{W} $</p></p> <p>Therefore, the average power dissipated by the circuit is $ 1 \, \text{W} $.</p>

About this question

Subject: Physics · Chapter: Alternating Current · Topic: AC Circuits: R, L, C

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