In the circuit shown, lamps L₁ and L₂, are identical. The sliding contact at O moved towards Q, then which of the statements about the effect on the brightness in L₂ is correct?

1. Initially it has no light, then its brightness increases gradually and becomes equal to that of L₁
2. Initially it is same as that of L₁, and finally become half as that of L₁
3. Initially it is half as that of L₁ and finally becomes equal to that of L₁.
4. Initially it is half as that of L₁ and finally becomes zero.

In which of the following figures shown, will the sound of a tuning fork hit with rubber pad at end A be heard maximum at end B?

1. I
2. II
3. Both I and II
4. Cannot be decided

When the displacement is along the opposite direction of the force, then the work is said to be

1. zero
2. negative
3. positive
4. infinite

In a radioactive decay, the atomic number of parent nuclei is not changed. The radiation emitted will be

1. β-rays
2. γ-rays
3. α-rays
4. the atomic number is affected by all forms of radioactive decay