Two points separated by a distance of 0.1 mm can just be seen in microscope when light of wavelength $6000 \mathop A\limits^o $ is used. If the light of wavelength $4800 \mathop A\limits^o $ is used, the limit of resolution will become

In the following circuit, the current $\mathrm{I_2}$ is

The first operation involved in a carnot cycle is

The gravitational potential energy required to raise a satellite of mass ' $m$ ' to height ' $h$ ' above the earth's surface is ' $\mathrm{E}_1$ '. Let the energy required to put this satellite into the orbit at the same height be ' $E_2$ '. If $M$ and $R$ are the mass and radius of the earth respectively then $E_1: E_2$ is