The velocity of certain ions that pass undeflected through crossed electric field $E = 7.7 \, kV/m$ and magnetic field $B = 0.14 \, T$ is.....$km/s$

An electron $(e^-)$ is moving in the North direction and the magnetic field at this place is in the upward direction. Then,the electron $(e^-)$ will be deviated towards:

$A$ charged particle is moving in a uniform magnetic field in a circular path of radius $R$. When the kinetic energy of the particle is increased to three times,then the new radius will be

Two ions having masses in the ratio $1: 1$ and charges $1: 2$ are projected into a uniform magnetic field perpendicular to the field with speeds in the ratio $2: 3$. The ratio of the radii of circular paths along which the two particles move is :

An electron $(q = 1.6 \times 10^{-19}\, C)$ is moving at a right angle to a uniform magnetic field of $3.534 \times 10^{-5}\, T$. The time taken by the electron to complete one circular orbit is ...... $\mu s$.

${H^ + },\,H{e^ + }$ and ${O^{ + + }}$ ions having same kinetic energy pass through a region of space filled with a uniform magnetic field $B$ directed perpendicular to the velocity of the ions. The masses of the ions ${H^ + },\,H{e^ + }$ and ${O^{ + + }}$ are respectively in the ratio $1:4:16$. As a result: