$A$ proton moving in a perpendicular magnetic field possesses energy $E$. The strength of the magnetic field is increased four times, but the proton is constrained to move in a path of the same radius. The kinetic energy of the proton will increase by: (in $\times$)

$A$ particle with charge $-Q$ and mass $m$ enters a magnetic field of magnitude $B$, which exists only to the of the boundary $YZ$. The direction of the motion of the particle is perpendicular to the direction of $B$. Let $T = 2\pi \frac{m}{QB}$. The time spent by the particle in the field will be:

In the given figure,an electron enters a magnetic field directed into the plane of the paper. It deflects in which direction?

In a region,there are uniform and constant electric and magnetic fields. Both these fields are parallel to each other. $A$ stationary charged particle is released in this region. The path of the particle will be.......

An electron and a proton enter a magnetic field perpendicularly. Both have the same kinetic energy. Which of the following is true?

Two particles $X$ and $Y$ having equal charges are being accelerated through the same potential difference. Thereafter,they enter normally into a region of uniform magnetic field and describe circular paths of radii $R_1$ and $R_2$ respectively. The mass ratio of $X$ and $Y$ is: