Under the influence of a uniform magnetic field, a charged particle moves with constant speed v in a circle of radius R. The time period of rotation of the particle

A galvanometer havings a coil resistance of 60 $$\Omega $$ shows full scale deflection when a current of 1.0 amp passes through it. It can be converted into an ammeter to read currents upto 5.0 amp by

The magnetic force acting on a charged particle of charge $$-$$2 $$\mu $$C in a magnetic frield of 2 T acting in y direction, when the particle velocity is $$\left( {2\widehat i + 3\widehat j} \right) \times {10^6}\,m{s^{ - 1}}$$

A galvanometer of resistance 50 $$\Omega $$ is connected to a battery of 3 V along with a resistance of 2950 $$\Omega $$ in series. A full scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be