If energy in the universe is constant, why is the world yelling out for energy crisis? What does judicious use of energy imply?
The energy in the universe is constant. However, when energy is converted into non-usable forms and cannot be converted back into usable forms, it gets wasted. If all the energy available is in non-usable form, we suffer the crisis for usable form of energy.
Judicious use of energy implies minimisation of wastage of energy by controlled use of sources and enabling reuse of energy wherever possible.