Moving Charge in a Magnetic Field question from JEE Main 2021 (25 Feb, Shift 1)

Answer: (a)

1. Equal momentum: $v = \dfrac{p}{m} \Rightarrow v \propto \dfrac{1}{m}$: $1 : \dfrac{1}{2} : \dfrac{1}{4} = 4 : 2 : 1$.
2. Force $F = qvB = \dfrac{qpB}{m} \Rightarrow F \propto \dfrac{q}{m}$: $\dfrac{1}{1} : \dfrac{1}{2} : \dfrac{2}{4} = 2 : 1 : 1$.
3. So the answer is (a) 2 : 1 : 1 and 4 : 2 : 1.