Two ions of masses 4 amu and 16 amu have charges +2e and +3e respectively. These ions pass through the region of constant perpendicular magnetic field. The kinetic energy of both ions is same. Then: (a) lighter ion will be deflected less than heavier ion (b) lighter ion will be deflected more than heavier ion (c) both ions will be deflected equally (d) no ion will be deflected

Answer: (b). Equal K: r ∝ √(m)/q. Lighter ion: √(4)/2 = 1; heavier ion: (√(16))/(3) = 4/3. The lighter ion has the smaller radius, so its path bends more. So the answer is (b) lighter ion will be deflected more than heavier ion.

Two ions of masses 4 amu and 16 amu have charges +2e and +3e… | JEE Main 2021 (27 Aug, Shift 1)

Q68JEE Main 2021 · 27 AUG · SHIFT 1Medium

Moving Charge in a Magnetic Field

Two ions of masses 4 amu and 16 amu have charges +2e and +3e respectively. These ions pass through the region of constant perpendicular magnetic field. The kinetic energy of both ions is same. Then:

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Answer: (b)

Equal $K$ : $r \propto \dfrac{\sqrt{m}}{q}$ .
Lighter ion: $\dfrac{\sqrt{4}}{2} = 1$ ; heavier ion: $\dfrac{\sqrt{16}}{3} = \dfrac{4}{3}$ .
The lighter ion has the smaller radius, so its path bends more.
So the answer is (b) lighter ion will be deflected more than heavier ion.

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Moving Charge in a Magnetic Field question from JEE Main 2021 (27 Aug, Shift 1)

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