State two characteristics of a good thermion emitter.

State two factors upon which the rate of emission of thermions depends.

A uniform half metre rule balances horizontally on a knife edge at 29 cm mark when a weight of 20 gf is suspended from one end.

(i) Draw a diagram of the arrangement.

(ii) What is the weight of the half metre rule?

(i) A boy uses a single fixed pulley to lift a load of 50 kgf to some height. Another boy uses a single movable pulley to lift the same load to the same height. Compare the effort applied by them. Give a reason to support your answer.

(ii) How does uniform circular motion differs from uniform linear motion?

(iii) Name the process used for producing electricity using nuclear energy.