Question

Two particles of masses $ m_a $ and $ m_b $ and same charge are projected in a perpendicular magnetic field. They travel along circular paths of radius $ r_a $ and $ r_b $ such that $ r_a > r_b $ . Then which is true?

• A. $ m_av_a > m_bv_b $
• B. $ m_a > m_b $ and $ v_a > v_b $
• C. $ m_a = m_b $ and $ v_a > v_b $
• D. $ m_bv_b > m_av_a $

Answer 1

Answer: (A)

Radius of circular path $ r_a= \frac {m_av_a}{qB} $
and $ r_b= \frac {m_bv_b}{qB} $
According to questions
$ r_a>r_b $
$ \therefore \frac {m_av_a}{qB}> \frac {m_bv_b}{qB} $
or $ m_av_a>m_bv_b $