. When rails are laid down on the ground, space is left between the end of two rails.

2. The transmission cables are not tightly fixed to the poles.

3. The iron rim to be put on a cart wheel is always of slightly smaller diameter than that of wheel.

4. A glass stopper jammed in the neck of a glass bottle can be taken out by warming the neck of the bottles.

Important Points

• Due to increment in its time period a pendulum clock becomes slow in summer and will lose time.
• Loss of time in a time period ΔT =(1/2)α ΔθT

∴ Loss of time in any given time interval t can be given by ΔT = (1/2) α Δθt

• At some higher temperature a scale will expand and scale reading will be lesser than true values, so that true value = scale reading (1 + α Δt) Here, Δt is the temperature difference.

However, at lower temperature scale reading will be more or true value will be less