Alternating Currents

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Alternating current (AC) is an electric current whose magnitude changes continuously with time and direction reverses periodically. It is typically represented as a sinusoidal function like $ I = I_m …

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The peak value ($ V_m $ or $ I_m $) is the maximum amplitude of AC voltage or current. The rms (root mean square) value is the effective steady DC equivalent that delivers the same average power. The …

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Given: $ V_m = 310 \text{V} $ Formula: $ V_{\text{rms}} = \frac{V_m}{\sqrt{2}} $ Step 1: $ V_{\text{rms}} = \frac{310}{\sqrt{2}} $ Step 2: $ \sqrt{2} \approx 1.414 $, so $ V_{\text{rms}} = \frac{31…

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The average value of a sinusoidal AC over one complete cycle is zero because the positive and negative halves cancel each other. However, AC still delivers power. The rms value accounts for the heatin…

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Although the instantaneous current passes through zero twice per cycle, the filament of the bulb does not cool down enough in such a short time (1/100 second for 50 Hz) to stop glowing. Due to thermal…

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The instantaneous alternating voltage is given by: $$ V = V_m \cos \omega t $$ The instantaneous alternating current is: $$ I = I_m \cos \omega t $$ Where: - $ V_m $, $ I_m $: peak voltage and cur…

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The frequency of AC in India is 50 Hz. This means the current completes 50 full cycles per second. Since the direction changes twice in one cycle (positive to negative and back), the current changes d…

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In a pure resistor, the voltage and current are in phase. This means they reach their maximum, minimum, and zero values at the same time. The phase difference is zero. This happens because Ohm’s law (…