Question

As shown in the figure, a magnet is brought towards a fixed coil. Due to this, the induced emf, current and the charge are $E$, $I$ and $Q$ respectively. If the speed of the magnet is doubled, then which of the following statements is wrong?

• A. $E$ increases.
• B. $I$ increases.
• C. $Q$ increases.
• D. None of the above

Answer 1

The correct option is C $Q$ increases.

When the speed of magnet is doubled, the rate of change of magnetic flux linked with the coil, is also doubled.

With the increase in the time rate of change flux, both induced emf and current will increase.

But the induced charge does not depend upon time, as induced charge in the coil depends upon the final and initial flux only, which is same in both the cases. So, it would remain the same.

Hence, $Q$ remains same while $E$ and $I$ will increase.

Hence, option ($C$) is the correct answer.