PhysicsHardHigh School (11–12)Electricity & Magnetism › Alternating CurrentJEE MainNEETAEEE (Amrita)AMUEEEAP EAPCETBCECE
Created by StemPy LabA heater coil of resistance carries a current : a steady part with an alternating part added to it. Take the average over a whole number of cycles. All the energy is dissipated as heat. The rms value of a current is the steady current that would give the same average heating. What is the average power dissipated in the coil?
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← A long air-cored solenoid has N turns, length l and area A. Six statements about changes follow. (i) Doubling N makes the self-inductance L four times as large. (ii) Doubling the radius makes L twice as large. (iii) Doubling the length, with N and A fixed, halves L. (iv) Doubling the current doubles the stored energy. (v) A short iron core in its middle multiplies L by µr. (vi) L depends on the current in an air-cored solenoid. How many of the statements above are correct?A resistor, an inductor and a capacitor are joined in series to a source of fixed rms voltage and variable frequency. The resistance is small. Two statements about the arrangement are given below.
Statement I: At resonance, the rms voltage across the inductor can be larger than the rms voltage of the source.
Statement II: Below the resonant frequency the current leads the source voltage, and above it the current lags the source voltage. →
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