CBSE 2024 · Region 2 · Set 1 · Q15 · 1 mark

Assertion (A) : An electron and a proton enter with the same momentum $\displaystyle \overrightarrow{\mathrm{p}}$ in a magnetic field $\displaystyle \overrightarrow{\mathrm{B}}$ such that $\displaystyle \overrightarrow{\mathrm{p}} \perp \overrightarrow{\mathrm{B}}$. Then both describe a circular path of the same radius. Reason $\displaystyle (R)$ : The radius of the circular path described by the charged particle (charge q , mass m ) moving in the magnetic field $\displaystyle \overrightarrow{\mathrm{B}}$ is given by $\displaystyle \mathrm{r}=\frac{\mathrm{mv}}{\mathrm{qB}}$.

CBSE Class 12 Physics past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.