A deuteron and an alpha particle having equal kinetic energy enter perpendicular into a magnetic field. Let $r_{d}$ and $r_{\alpha}$ be their respective radii of circular path. The value of $\frac{r_{d}}{r_{\alpha}}$ is equal to

An electron, a proton, a deuteron and an alpha particle, each having the same speed are in a region of constant magnetic field perpendicular to the direction of the velocities of the particles. The radius of the circular orbits of these particles are respectively $R_e, R_p, R_d \,$ and $\, R_\alpha$. It follows that

An electron (mass = $9.0 × $${10^{ – 31}}$ $kg$ and charge =$1.6 \times {10^{ – 19}}$ $coulomb$) is moving in a circular orbit in a magnetic field of $1.0 \times {10^{ – 4}}\,weber/{m^2}.$ Its period of revolution is

A charged particle enters a uniform magnetic field with velocity vector making an angle of $30^o$ with the magnetic field. The particle describes a helical trajectory of pitch $x$ . The radius of the helix is

An electron is travelling horizontally towards east. A magnetic field in vertically downward direction exerts a force on the electron along