A cell of internal resistance 1Ω supplies current to an external resistor of 3Ω. The efficiency of the cell is

A conductor of length 2m carries a current of 0.8A while kept in a magnetic field of magnetic flux density 0.5T. The maximum force acting on it is

Light of energy 5eV falls on a metal of work function 3eV and electrons are liberated. The stopping potential is

The height at which the atmosphere ceases to exist is about 80km. If the atmospheric pressure on the ground level is 760mmHg, the pressure at a height of 20km above the ground level is

A stone of mass 1kg is dropped from a height of 10m above the ground and falls freely under gravity. Its kinetic energy 5m above the ground is then equal to