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Power in AC Circuits for JEE: 30 solved questions

Real JEE paper questions on power in ac circuits, part of alternating current. Each opens with the options, the correct answer and a step-by-step solution. Papers run from 2002 to 2026. No sign-in needed to read them.

What this topic asks

• Average power and heating — 15 questions
• Power factor — 11 questions
• Wattless current — 4 questions

All 30 questions with solutions

• A series circuit driven at Eᵣₘₛ=90 V, f=30 Hz has R=80 Ω, inductive reactance X_L=20.0 Ω and capacitive react… JEE Main 6th April 1st Shift 2026
• For a series LCR circuit connected to a 220 V, 50 Hz a.c. source (see figure) with X_L=70 Ω, X_C=150 Ω and R=… JEE Main 24th Jan 2nd Shift 2026
• In an a.c. circuit the voltage and current are V=100 sin(100t) V and I=100 sin (100t+π/3) mA. The average pow… JEE Main 29th Jan 2nd Shift 2024
• A series LR circuit driven by E=(25 sin 1000t) V has power factor 1/(√2). If the source is changed to E=(20 s… JEE Main 30th Jan 1st Shift 2024
• An a.c. voltage V=20 sin(200π t) V applied to a series LCR circuit drives a current I=10 sin (200π t+π/3) A.… JEE Main 31st Jan 2nd Shift 2024
• Statement I: Maximum power is dissipated in a series LCR circuit with an a.c. source when resonance occurs. S… JEE Main 10th April 1st Shift 2023
• In a series LR circuit with X_L=R the power factor is P₁. A capacitor with X_C=X_L is then added in series an… JEE Main 30th Jan 1st Shift 2023
• Statement-I: The reactance of a circuit is zero; it is possible that the circuit contains a capacitor and an… JEE Main 24th June 2nd Shift 2022
• If a wattless current flows in an a.c. circuit, the circuit is JEE Main 25th June 1st Shift 2022
• In a series LCR circuit X_L=10 Ω, X_C=4 Ω and R=6 Ω. The power factor is JEE Main 18th March 1st Shift 2021
• A 750 Hz, 20 V (r.m.s.) source drives a series circuit of R=100 Ω, L=0.1803 H and C=10 μF. The time for the r… JEE Main 3rd Sept 1st Shift 2020
• One kg of water at 20°C is heated in a kettle whose element has mean resistance 20 Ω; the mains r.m.s. voltag… JEE Main 12th April 2nd Shift 2019
• A series a.c. circuit has an inductor (20 mH), a capacitor (120 μF) and a resistor (60 Ω), driven by 24 V/50… JEE Main 9th Jan 2nd Shift 2019
• In an a.c. circuit the instantaneous emf and current are e=100 sin 30t and i=20 sin (30t-π/4). In one cycle,… JEE Main 2019 (paper/shift not legible in scan)
• In the LCR circuit shown (see figure) the current leads the applied voltage. Adding a capacitor C' to the exi… JEE Main Online 2015
• A series LR circuit at frequency ω has inductive reactance 2R. A capacitor of capacitive reactance R is then… JEE Main Online 2013
• A series LCR circuit has R=200 Ω across a 220 V, 50 Hz supply. Removing the capacitor makes the current lag b… AIEEE 2010
• In an a.c. circuit the applied voltage is E=E₀ sin ω t and the current is I=I₀ sin (ω t-π/2). The power consu… AIEEE 2007
• A circuit has a resistance of 12 Ω and an impedance of 15 Ω. The power factor is AIEEE 2005
• The power factor of an a.c. circuit with resistance R and inductance L in series at angular frequency ω is AIEEE 2002
• An inductor of reactance 100 Ω, a capacitor of reactance 50 Ω and a resistor of 50 Ω are in series with a 10… JEE Main 7th April 2nd Shift 2025
• A capacitor of reactance 4√3 Ω and a resistor of 4 Ω are in series with an a.c. source of peak value 8√2 V. T… JEE Main 9th April 2nd Shift 2024
• A series LCR circuit with L=(100)/π mH, C=(10⁻³)/π F and R=10 Ω is across a 220 V, 50 Hz supply. The power fa… JEE Main 27th Jan 2nd Shift 2024
• A series LCR circuit across a 220 V, 50 Hz source has R=80 Ω, X_L=70 Ω and X_C=130 Ω. The power factor is x/(… JEE Main 25th Jan 2nd Shift 2023
• A 220 V, 50 Hz source runs a 25 V, 5 W lamp in series with an additional resistance R (see figure) so the lam… JEE Main 27th June 1st Shift 2022
• An a.c. source V=20√2 sin(100t) drives a series circuit of L=100 mH, C=100 μF and R=120 Ω. The time in which… JEE Main 28th June 1st Shift 2022
• An a.c. circuit has an inductor and resistor R in series with X_L=3R. A capacitor with X_C=2R is then added i… JEE Main 27th Aug 2nd Shift 2021
• A series LCR circuit with R=5 Ω and L=20 mH is across a 250 V variable-frequency supply. The power dissipated… JEE Main 20th July 2nd Shift 2021
• A sinusoidal voltage of peak value 250 V is applied to a series LCR circuit with R=8 Ω, L=24 mH and C=60 μF.… JEE Main 16th March 1st Shift 2021
• In a series LR circuit, 400 W is dissipated from a 250 V, 50 Hz source at power factor 0.8. To raise the powe… JEE Main 6th Sept 2nd Shift 2020