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Magnetism

Cool goIITian

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2 Jan 2008 20:46:54 IST

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356

quite intriguing

None

when an alternating voltage is applied across a capacitor we say that the current leads the voltage by pi/2,so does it mean that there would be current without any voltage being applied?

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Tarin Bansal

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2 Jan 2008 22:01:10 IST

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No. What made U think so?

sudiv divakar

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2 Jan 2008 22:19:52 IST

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when we draw the graph we see that the current is maximum when the voltage is zero.

Tarin Bansal

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2 Jan 2008 22:28:11 IST

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Oh OK
Then the answer is yes.
But remember we are talking about AC SOURCE NOT DC. Frequency of AC source is high(that is our homes is 50Hz), it means that 50 cycles in 1 sec. So we can't notice the change appreciably.
And also don't use the phrase voltage is ZERO. See it happens like this-
Assume the frequency to be very small(like 1 cycle per minute or so). Now voltage varies sinusoidally. It means that now if voltage is zero, earlier it was at its maximum and at that time it was charging the capacitor. As the graph is constatly moving forward, the voltage decreases from max to zero while charging and at the time it reaches zero the capacitor was charged to give max current and this cylce goes on.

Any doubts?

Tarin Bansal

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2 Jan 2008 22:29:12 IST

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I must say that its a very gud doubt. Not many people notice what U noticed.

sudiv divakar

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2 Jan 2008 22:39:49 IST

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thanx doubts cleared.

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