Answer:
[tex]= 2.3 \times10 ^{-2}[/tex]
Explanation:
using formula  for radius
 r =  [tex]\frac{mv}{qB}[/tex]
  mv = qBr  (momentum)......(i)
 where m is mass   v is velocity  Â
q is charge    B is magnetic field
using relation b/w kinetic energy and momentum
      [tex]p = \sqrt{ 2 KE m}[/tex] ............(ii)
where p is momentum and
K.E is kinetic energy
since qB is same for electron and proton and energy is also     same(given) Â
from (i) and (ii) equation we get
[tex]qBr = \sqrt{2 KE m}[/tex]
[tex]r = \frac{\sqrt{2KE m} }{qB}[/tex]
since qB is same for electron and proton and energy is also     same(given) Â
so we get
r will be directly proportional to square root of mass m
[tex]\frac{r_e}{r_p} = \sqrt{\frac{m_{e}}{m_p} }[/tex]
     [tex]= \sqrt{\frac{9.1 \times 10^{-31}}{1.67 \times10^{{-27}}}[/tex]
     [tex]= 2.3 \times10 ^{-2}[/tex]
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