A charged particle of charge $\mathrm{e}$ and mass $\mathrm{m}$ is moving in an electric field ${{\rm{\vec E}}}$ and magnetic field ${{\rm{\vec B}}}$ Construct dimensionless quantities and quantities of dimension [T]-1
When electron enter in perpendicular magnetic field than magnetic force balance with centripetal force,
$\frac{m v^{2}}{\mathrm{R}}=q v \mathrm{~B}$
$\therefore\frac{q \mathrm{~B}}{m}=\frac{v}{\mathrm{R}}=\omega$
$\therefore\omega=\frac{v}{\mathrm{R}}=\frac{\mathrm{M}^{0} \mathrm{~L}^{1} \mathrm{~T}^{-1}}{\mathrm{~L}^{1}}=\mathrm{T}^{-1}$
Thus, angular frequency having dimension equal to $\mathrm{T}^{-1}$.
An electron is moving along positive $x$-axis.Auniform electric field exists towards negative $y$-axis. What should be the direction of magnetic field of suitable magnitude so that net force of electron is zero
The acceleration of an electron at a moment in a magentic field $\vec B\, = \,2\hat i + 3\hat j + 4\hat k$ is $\vec a\, = \,x\hat i - 2\hat j + \hat k$. The value of $x$ is
An electron with kinetic energy $5 \mathrm{eV}$ enters a region of uniform magnetic field of $3 \mu \mathrm{T}$ perpendicular to its direction. An electric field $\mathrm{E}$ is applied perpendicular to the direction of velocity and magnetic field. The value of $\mathrm{E}$, so that electron moves along the same path, is . . . . . $\mathrm{NC}^{-1}$.
(Given, mass of electron $=9 \times 10^{-31} \mathrm{~kg}$, electric charge $=1.6 \times 10^{-19} \mathrm{C}$ )
If a positive ion is moving, away from an observer with same acceleration, then the lines of force of magnetic induction will be
Two charged particles of mass $m$ and charge $q$ each are projected from origin simultaneously with same speed $V$ in transverse magnetic field. If ${\vec r_1}$ and ${\vec r_2}$ are the position vectors of particles (with respect to origin) at $t = \frac{{\pi m}}{{qB}}$ then the value of ${\vec r_1}.{\vec r_2}$ at that time is