Pendulum clocks become slow in summer because
- ADays in summer are large.
- BOf the friction in the coil.
- CThe length of the pendulum increases.
- DThe weight of the pendulum changes.
Show answer and explanation
Correct answer: (c) The length of the pendulum increases.
Explanation
In summer, heat causes thermal expansion, so the length of the pendulum increases.
Time period T = 2π√(l/g), so T ∝ √l; a longer pendulum has a larger time period and fewer oscillations per day.
The clock therefore runs slow in summer and fast in winter, when the length contracts.