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}
- (A)Time taken by them to reach the earth's surface will be independent of the properties of their materials
- (B)Insulating ball will reach the earth's surface earlier than the metal ball✓ Correct
- (C)Both will reach the earth's surface simultaneously
- (D)Metal ball will reach the earth's surface earlier than the insulating ball.
Answer: (B)
Solution
Both balls share the same mass and size, so gravity and the negligible air drag act identically; the only property that differs is their ability to conduct. As the metallic ball falls through the Earth's magnetic field, eddy currents are induced in it, and by Lenz's law these set up a force opposing its motion, so it is retarded. The insulating ball carries no such currents and falls freely. The insulating ball therefore reaches the ground earlier than the metallic ball.
JEE Main · 2023 · 31 Jan 2023 · Shift 1 · Single correct option