Question

A charged particle is moving in a uniform magnetic field in a circular path. Radius of circular path is R. When energy of particle is doubled, then new radius will be

• A. $R \sqrt { 2 }$
• B. $R \sqrt { 3 }$
• C. 2 R
• D. 3 R

Answer 1

Answer: (A)

$R \sqrt { 2 }$

Answer 2

$r = \frac { \sqrt { 2 m K } } { q B } \Rightarrow r \propto \sqrt { K }$ $\Rightarrow \frac { R } { R _ { 2 } } = \sqrt { \frac { K } { 2 K } } \Rightarrow R _ { 2 } = R \sqrt { 2 }$