AC voltage across a capacitor (derivation) | Alternating currents | Physics | Khan Academy

When an alternating voltage is applied across a capacitor, the current leads the voltage by a phase angle of 90 degrees. This means the current oscillates a quarter of the cycle ahead of the voltage. Let's derive an expression for this current.

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Created by Mahesh Shenoy

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[paloosalama]

Thanks for your effort!
I have a question: how is it possible in initial moment of time when V=0, I=max? In this point voltage difference is zero, so the capacitor wouldn't "know" how great it would be to "calculate" I max. Really really looking forward for your answer, thanks.

[romario]

what program have you used to create this presentation, please?

[saimaqadeer]

If voltage across capacitor is same as voltage generated then how the current would flow ???

[mohfa]

Thank you for your great educational lessons

I have question please : i am confused how we can write : Vs= Vc knowing that the capacitor "gradualy" raise its voltage and doesnt respond instantaneously with the voltage source !, why we are ignoring this fact and treating capacitor as if it is a resistor ?

Thank you in advance

[AmnaMohammed-lv]

How does alternating current arise the applied voltage equal to the voltage inside the coil and opposite in direction? And why

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[AmnaMohammed-lv]

How does alternating current arise when the applied voltage is equal in magnitude to the voltage inside the coil and opposite in direction?!

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4:53 i don't understand how sin becomes cos and why omega pops out

[chaudharymujeeb]

Why we change the function from sin to