The absolute zero, i.e. temperature below which is not achievable, is about

Lightning conductors are used to protect building from lightning strikes. Which of the following statement(s) is/are true about lightning conductors?

1. Lightning conductors create an electric field at its top, so that lightning strikes it preferentially.

2. Lightning conductors reduce the effect of the strike by uniformly distributing the charge (current) over the surface of the building.

3. Lightning conductors take all charges (current) to deep down in the earth.

4. Lightning conductors must be installed at a place taller than the building.

Select the correct answer using the codes given below

The silvering in thermo flask is done to avoid heat transfer by

Conservation of momentum in a collision between particles can be understood on the basis of