Question 1

The peak value of an alternating current is $I0$. Its root mean square (rms) value ($I{rms}$) is given by:

Accepted Answer

The relation between the rms value and the peak value of alternating current is $I{rms} = \frac{I0}{\sqrt{2}} \approx 0.707 I0$.

Question 2

The ratio of peak value to the rms value of an alternating current is:

Accepted Answer

Since $I{rms} = \frac{I0}{\sqrt{2}}$, the ratio of peak value ($I0$) to rms value ($I{rms}$) is $\frac{I0}{I{rms}} = \sqrt{2} : 1$.

Question 3

For a direct current (DC), the capacitive reactance ($XC$) is:

Accepted Answer

Capacitive reactance is given by $XC = \frac{1}{2\pi f C}$. For direct current (DC), frequency $f = 0$, so $XC = \frac{1}{0} = \infty$ (infinite).

Question 4

In a purely inductive AC circuit, the phase difference between current and voltage is:

Accepted Answer

In an AC circuit containing only an inductor, alternating voltage leads the current by a phase angle of $90^\circ$ or $\pi/2$ radians.

Question 5

The power factor of a purely capacitive AC circuit is:

Accepted Answer

For a purely capacitive circuit, the phase difference between voltage and current is $\phi = 90^\circ$. Therefore, Power factor = $\cos\phi = \cos 90^\circ = 0$.

Alternating Current — MP Board Class 12 Physics Important Questions & Revision Notes