JEE Main 2025 — Alternating Current Question with Solution

To find the peak current through the bulb, follow these steps:

Step 1: Calculate the bulb's rms (root mean square) current:

The formula to find the rms current is:

$$I_{\text{rms}}=\frac{P}{V}$$

Here, $P=100\text{ W}$ and $V=220\text{ V}$. Substitute these values into the formula:

$$I_{\text{rms}}=\frac{100\text{ W}}{220\text{ V}}\approx 0.455\text{ A}$$

Step 2: Convert the rms current to peak current:

Use the following formula to find the peak current:

$$I_{\text{peak}}=I_{\text{rms}}\times \sqrt{2}$$

Substitute the value of $I_{\text{rms}}$ into the formula:

$$I_{\text{peak}}=0.455\times 1.414\approx 0.64\text{ A}$$

The correct choice is 0.64 A (Option B).