Question

A particle moves in a circle of diameter 1.0 cm under the action of a magnetic field of 0.40 T. An electric field of $200V{m}^{-1}$ makes the path straight. Find the charge/mass ratio of the particle.

Answer 1

$r=0.5\times {10}^{-2}m,B=0.4t,E=200v/m$

The path will straighten if

$qE=qVB$

$\Rightarrow V=\frac{E}{B}=500m/s.$

Since, $r=\frac{mV}{qB}$

$\frac{q}{m}=\frac{V}{rB}=2.5\times {10}^{5}C/kg$