When a charge of $$3 ~\mathrm{C}$$ is placed in uniform electric field, it experiences a force of $$3000 \mathrm{~N}$$. Within this field, potential difference between two points separated by a distance of $$1 \mathrm{~cm}$$ is

A soap bubble of radius '$$R$$' is blown. After heating a solution, a second bubble of radius '$$2 \mathrm{R}$$' is blown. The work required to blow the $$2^{\text {nd }}$$ bubble in comparison to that required for the $$1^{\text {st }}$$ bubble is

In a transistor, in common emitter configuration, the ratio of power gain to voltage gain is

A galvanometer of resistance $$20 ~\Omega$$ gives a deflection of 5 divisions when $$1 \mathrm{~mA}$$ current flows through it. The galvanometer scale has 50 divisions. To convert the galvanometer into a voltmeter of range 25 volt, we should connect a resistance of