Spherical insulating ball and a spherical metallic ball of same size and mass are dropped from the same height. Choose the correct statement out of the following {Assume negligible air friction}

Solution :

with negligible air resistance, all bodies fall with same acceleration :

$$g$$

However, since one ball is metallic (conducting) and the other is insulating, electromagnetic effects must also be considered.

As the metallic ball falls through Earth’s magnetic field, the magnetic flux linked with different parts of the conductor changes.

This induces eddy currents inside the metallic ball.

According to Lenz’s law, these induced currents oppose the motion producing them.

Hence, an upward magnetic retarding force acts on the metallic ball.

Therefore, acceleration of metallic ball becomes :

$$a_{\text{metal}} < g$$

For insulating ball, no eddy currents are produced.

Hence,

$$a_{\text{insulating}} = g$$

Therefore, insulating ball reaches the ground slightly earlier than the metallic ball.

Final Answer :

Insulating ball will reach the earth’s surface earlier than the metallic ball.