If the direction of the initial velocity of the charged particle is perpendicular to the magnetic field, then the orbit will be   or  The path executed by a charged particle whose motion is perpendicular to magnetic field is

A small block of mass $m$, having charge $q$ is placed on frictionless inclined plane making an angle  $\theta$ with the horizontal. There exists a uniform magnetic field $B$ parallel to the inclined plane but  perpendicular to the length of spring. If $m$ is slightly pulled on the inclined in downward direction and released, the time period of oscillation will be (assume that the block does not leave contact with the plane)

A charge particle projected with velocity $\vec v$ in uniform magnetic field ' $\vec B$ ' then for maximum magnetic force on it, which is correct

A charged particle is moving in a uniform magnetic field in a circular path. Radius of circular path is $R$. When energy of particle is doubled, then new radius will be

An electron having mass $m$ and kinetic energy $K$ enter in uniform magnetic field $B$ perpendicularly, then its frequency will be

A long solenoid has $100\,turns/m$ and carries current $i.$ An electron moves with in the solenoid in a circle of radius $2·30\,cm$ perpendicular to the solenoid axis. The speed of the electron is $0·046\,c$ ($c =$ speed of light). Find the current $i$ in the solenoid (approximate).....$A$