Question

A sine wave voltage is applied across a capacitor. When the frequency of the voltage is decreased, what happens to the current?

Answer 1

If the frequency of voltage is decreased, then current value is also `color(blue)(decreased)`.

Explanation:

If the opposition to applied voltage is increased, then current value is decreased.

Here,the opposition is due to reactance of capacitor.

`X_c=1/(2pifC)`

`X_c`=reactance of capacitor,

`f`=frequency of applied voltage.

`X_cprop1/f`[since`1/(2piC)=`constant]`" "color(blue)((1))`

From ohm's law,

`V=I_cX_c`

`X_c=V/I_c`

`X_cprop1/I_c`[since V is constant]`" "color(blue)((2))`

From `" "color(blue)((1))`&`color(blue)((2))`;

`1/fprop1/I_C`

`color(green)(I_cpropf)`

From above relation,

If the frequency of voltage is decreased, then current value is also `color(blue)(decreased)`.