For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (U_e) and magnetic (U_m) fields is :

The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation :

An RC circuit as shown in the figure is driven by a AC source generating a square wave. The output wave pattern monitored by CRO would look close to :

One main scale division of a vernier callipers is 'a' cm and n^th division of the vernier scale coincide with (n $$-$$ 1)^th division of the main scale. The least count of the callipers in mm is :