Question

A proton of charge $e$ and mass $m_p$ moves in a circular path of radius $r$ in a uniform magnetic field $B$.
The momentum of the proton can be described by the expression:

• A. $eBr$
• B. $2eBr$
• C. $eB{r}^2$
• D. $eBr{m}_p$
• E. $2eBr{m}_p$

Answer 1

Answer: (A)

$eBr$

Momentum of the proton $P=m_{p}v$

Using $eBr=m_{p}v$

$⟹$ $P=eBr$