What is the radius of the path of an electron (mass $9 \times 10^{-31}\;kg$ and charge $1.6 \times 10^{-19} \;C )$ moving at a speed of $3 \times 10^{7} \;m / s$ in a magnetic field of $6 \times 10^{-4}\;T$ perpendicular to it? What is its frequency? Calculate its energy in $keV$. ( $\left.1 eV =1.6 \times 10^{-19} \;J \right)$
$r=m v /(q B)$$=9 \times 10^{-31} kg \times 3 \times 10^{7} m s ^{-1} /\left(1.6 \times 10^{-19} C \times 6 \times 10^{-4} T \right)$
$=26 \times 10^{-2}\, m =26 \,cm$
$v=v /(2 \pi r)=2 \times 10^{6}\, s ^{-1}$$=2 \times 10^{6} Hz =2 \,MHz$
$E=(1 / 2) m v^{2}=(1 / 2) 9 \times 10^{-31} \,kg \times 9 \times 10^{14} \,m ^{2} / s ^{2}$$=40.5 \times 10^{-17}\, J$
$\approx 4 \times 10^{-16} \,J =2.5 \,keV$
Two particles of charges $+Q$ and $-Q$ are projected from the same point with a velocity $v$ in a region of uniform magnetic field $B$ such that the velocity vector makes an angle $q$ with the magnetic field. Their masses are $M$ and $2M,$ respectively. Then, they will meet again for the first time at a point whose distance from the point of projection is
An electron is projected with velocity $\vec v$ in a uniform magnetic field $\vec B$ . The angle $\theta$ between $\vec v$ and $\vec B$ lines between $0^o$ and $\frac{\pi}{2}$ . It velocity $\vec v$ vector returns to its initial value in time interval of
Two charged particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field $B = B_0 \hat k$ .
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 $=1.6 \times 10^{-19} \mathrm{C}$ )
Explain electric field and its source as well as magnetic field and its source.