Question

a bulb and a capacitor are connected in series to an a.c. source of variable frequency. how will the brightness of the bulb change on increasing the frequency of the a.c. source? give reason.

Answer 1

answer of the above question

Answer 2

Answer:

The brightness will increase with the increase in frequency.

Explanation:

According to the given problem

Bulb and capacitor are connected in series with variable frequency ac source.

In this case the total impedance of the circuit can be given by

$|Z|\ =\ \sqrt{R^2+(\dfrac{1}{2.\pi.f.c})^2}$

So, the total impedance of the circuit will depend upon the frequency and as the frequency will increase the impedance will decrease and vice-versa.

$P\ =\ \dfrac{V^2}{|Z|}$

So, the power will be inversely proportional to the impedance and hence, if the impedance will decrease then the power will increase and so the brightness and vice versa.

So, with the increase in frequency brightness will increase.