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JEE Main 2022 (28 Jun, Shift 1) · Power, Power Factor & Wattless Current

Power, Power Factor & Wattless Current question from JEE Main 2022 (28 Jun, Shift 1)

Q55JEE Main 2022 · 28 JUN · SHIFT 1Difficult

Power, Power Factor & Wattless Current

An AC source is connected to an inductance of 100 mH, a capacitance of 100 μ\muF and a resistance of 120 Ω\Omega as shown in figure. The time in which the resistance having a thermal capacity 2 J/∘^\circC will get heated by 16∘^\circ C is _____________ s.

Figure

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

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Answer: 15

  1. ω=100\omega = 100: XL=10 ΩX_L = 10\ \Omega, XC=1100×10−4=100 ΩX_C = \frac{1}{100\times 10^{-4}} = 100\ \Omega
  2. Z=1202+902=150 ΩZ = \sqrt{120^2 + 90^2} = 150\ \Omega, Vrms=20V_{rms} = 20 V, I=20150=215I = \frac{20}{150} = \frac{2}{15} A
  3. P=I2R=4225×120=3215P = I^2R = \frac{4}{225}\times 120 = \frac{32}{15} W
  4. Heat needed =2×16=32= 2\times 16 = 32 J, t=32÷3215=15t = 32 \div \frac{32}{15} = 15 s
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