Two micrometers are shown in figures given below. Give the actual reading shown provided :

(a) The least count of the instrument = 0.001 cm and zero error = +0.05 mm.

(b) The least count of the instrument = 0.001 cm and zero error = -0.021 cm.

Figure below shows the reading obtained while measuring the diameter of a wire with a screw gauge. The screw advances by 1 division on main scale when circular head is rotated once.

Find —

(i) pitch of the screw gauge,

(ii) least count of the screw gauge, and

(iii) the diameter of the wire.

The pendulum used in a clock is:

1. Simple pendulum
2. Compound pendulum
3. Second pendulum
4. None of these

The effective length of a pendulum is related with time period as :

1. T² ∝ l²
2. T³ ∝ l
3. T² ∝ l
4. T ∝ L³