In a crossed field, the magnetic field induction is $2.0 \mathrm{~T}$ and electric field intensity is $20…
In a crossed field, the magnetic field induction is $2.0 \mathrm{~T}$ and electric field intensity is $20 \times 10^3 \mathrm{~V} / \mathrm{m}$. At which velocity the electron will travel in a straight line without the effect of electric and magnetic fields?
$\frac{20}{16} \times 10^3 \mathrm{~ms}^{-1}$
$10 \times\ 10^3\ ms^{-1}$
$20 \times\ 10^3\ ms^{-1}$
$40 \times\ 10^3\ ms^{-1}$
Solution
$e V B=e E$
where, $e=$ electronic charge and $v=$ velocity of electron
$\Rightarrow \quad v=\frac{E}{B} v=\frac{20 \times 10^3}{2.0}=10 \times 10^3 \mathrm{~ms}^{-1}$