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JEE Main 2022 (27 Jul, Shift 1) · Power, Power Factor & Wattless Current

Power, Power Factor & Wattless Current question from JEE Main 2022 (27 Jul, Shift 1)

Q54JEE Main 2022 · 27 JUL · SHIFT 1Medium

Power, Power Factor & Wattless Current

To light, a 50 W,100 V50\text{ W}, 100\text{ V} lamp is connected, in series with a capacitor of capacitance 50πx μF\frac{50}{\pi\sqrt{x}}\ \mu F, with 200 V,50 Hz AC200\text{ V}, 50\text{ Hz AC} source. The value of xx will be ___________.

Numerical answer type. Work it out, then open the answer.

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Answer: 3

  1. Lamp: R=V2/P=1002/50=200 ΩR = V^2/P = 100^2/50 = 200\ \Omega, I=P/V=0.5I = P/V = 0.5 A.
  2. Z=200/0.5=400 ΩZ = 200/0.5 = 400\ \Omega
  3. XC=4002−2002=2003 ΩX_C = \sqrt{400^2-200^2} = 200\sqrt{3}\ \Omega
  4. C=12πfXC=1100π×2003C = \frac{1}{2\pi f X_C} = \frac{1}{100\pi\times 200\sqrt{3}} F =50π3 μ= \frac{50}{\pi\sqrt{3}}\ \muF
  5. So x=3x = 3.
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