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⚛️ Physics  ·  Alternating Current  ·  NEET & JEE

A coil in an AC generator produces an RMS emf of 70.7 V and is connected to a 50 Ω purely resistive load. What is the RMS current?

Answer: 1.41 A.

  • A 0.707 A
  • B 1.41 A
  • C 1.00 A
  • D 3.54 A

Correct answer: B. 1.41 A

Explanation: For a purely resistive load, I<sub>rms</sub> = V<sub>rms</sub>/R = 70.7/50 = 1.414 A, approximately 1.41 A.

V and I Phase Relationships in AC CircuitsPure Inductor: I lags V by 90°VIPure Capacitor: I leads V by 90°VIMemory aid "ELI the ICE man": in an inductor (L) E(V) leads I; in a capacitor (C) I leads E(V)For a pure resistor, V and I stay perfectly in phase (no lag or lead at all)

In a pure inductor the current lags the voltage by 90° (energy is briefly stored in the magnetic field before current responds); in a pure capacitor the current leads the voltage by 90° (current must flow to build up charge before voltage rises) - the mnemonic "ELI the ICE man" keeps these straight.

Concept context

AC circuits, impedance, LCR series circuit, resonance, transformers, and power factor.

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