An electron beam is moving between two parallel plates having an electric field of $1.125 \times 10^{-6} \, N/C$. $A$ magnetic field of $3 \times 10^{-10} \, T$ is also applied so that the beam of electrons does not deflect. The velocity of the electron is ............ $m/s$.

$A$ particle of mass $m$ and charge $q$ moves with a constant velocity $v$ along the positive $x$ direction. It enters a region containing a uniform magnetic field $B$ directed along the negative $z$ direction,extending from $x = a$ to $x = b$. The minimum value of $v$ required so that the particle can just enter the region $x > b$ is

$A$ charged particle moves through a magnetic field perpendicular to its direction. Then

An alpha particle moving with a certain speed towards the east enters a uniform magnetic field directed vertically up. The alpha particle will then move in:

Which of the following statements is true?

An electron is projected with velocity $\vec{v}$ in a uniform magnetic field $\vec{B}$. The angle $\theta$ between $\vec{v}$ and $\vec{B}$ lies between $0^\circ$ and $\frac{\pi}{2}$. Its velocity vector $\vec{v}$ returns to its initial value in a time interval of: