JEE Main2013PhysicsOscillationsActual
Bob of a simple pendulum of length l is made of iron. The pendulum is oscillating over a horizontal coil carrying direct current. If the time period of the pendulum is T then :
Options
- AT < 2 l g and damping is smaller than in air alone.
- BT=2 l g and damping is larger than in air alone.
- CT>2 l g and damping is smaller than in air alone.
- DT < 2 l g and damping is larger than in air alone.
Correct answer
D. T < 2 l g and damping is larger than in air alone.
Step-by-step solution
When the pendulum is oscillating over a current carrying coil, and when the direction of oscillating pendulum bob is opposite to the direction of current. Its instantaneous acceleration increases. Hence time period T < 2 g and damping is larger than in air alone due energy dissipation.