Verified Solution • 2025–26 Session moderate

QJEEM12Ph4298: JEE Main 2012 Physics - Class 12 JEEM12Ph4298 Solution: Proton, deuteron and alpha particle of same kinetic energy are…

Proton, deuteron and alpha particle of same kinetic energy are moving in circular trajectories in a constant magnetic field. The radii of proton, denuteron and alpha particle are respectively rp,rd{r_p},{r_d} and rα{r_\alpha } . Which one of the following relation is correct?

Multiple Choice Options

  • A rα=rp=rd{r_\alpha } = {r_p} = {r_d}
  • B rα=rp<rd{r_\alpha } = {r_p} < {r_d}
  • C rα>rd>rp{r_\alpha } > {r_d} > {r_p}
  • D rα=rd>rp{r_\alpha } = {r_d} > {r_p}

Step-by-Step Verified Solution

r=2mvqB⇒r×vmqr = {{\sqrt {2mv} } \over {qB}} \Rightarrow r \times v{{\sqrt m } \over q}

Thus we have, {r_\alpha } = {r_p} &lt; {r_d}

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