A charge particle projected with velocity $\vec v$ in uniform magnetic field ' $\vec B$ ' then for maximum magnetic force on it, which is correct
$\vec v.\vec B = 0$
$\vec v \times \vec B = 0$
$\vec v||\vec B$
$\vec v$ is anti parallel to $\vec B$
The region between $y = 0$ and $y = d$ contains a magnetic field $\vec B = B\hat z$ A particle of mass $m$ and charge $q$ enters the region with a velocity $\vec v = v\hat i$. If $d = \frac{{mv}}{{2qB}}$ , the acceleration of the charged particle at the point of its emergence at the other side is
A particle is moving in a uniform magnetic field, then
A collimated beam of charged and uncharged particles is directed towards a hole marked $P$ on a screen as shown below. If the electric and magnetic fields as indicated below are turned $ON$
An electron moving with a uniform velocity along the positive $x$-direction enters a magnetic field directed along the positive $y$-direction. The force on the electron is directed along
An electron is moving with a speed of ${10^8}\,m/\sec $ perpendicular to a uniform magnetic field of intensity $B$. Suddenly intensity of the magnetic field is reduced to $B/2$. The radius of the path becomes from the original value of $r$