Question

Proton, denteron and alpha particles of the same kinetic energy and moving in circular trajectories in a constant magnetic field. The radii of proton, denteron and alpha particles are respectively $r_p,r_d$ and $r_{\alpha }.$ Which one of the following relations is correct ?

• A. $r_{\alpha }=r_p=r_d$
• B. $r_{\alpha }=r_p<r_d$
• C. $r_{\alpha }>r_d>r_p$
• D. $r_{\alpha }=r_d>r_p$

Answer 1

The correct option is B $r_{\alpha }=r_p<r_d$

$r=\frac{\sqrt{2mK}}{Bq}$
$r\propto \frac{\sqrt{m}}{q}$
$r_{\alpha }=r_p<r_d$