JEE Main 2022 · 24 Jun · Shift 2 · Physics Q39

← JEE Main 2022 · 24 Jun · Shift 2

PhysicsSingle correct+4 / -1Question 39 of 90

A proton, a deuteron and an $\alpha$ -particle with same kinetic energy enter into a uniform magnetic field at right angle to magnetic field. The ratio of the radii of their respective circular paths is :

1:\sqrt2:\sqrt2

1:1:\sqrt2

\sqrt2:1:1

1:\sqrt2:1

Answer and worked solution

Official answer: D

Radius. $r=\dfrac{mv}{qB}=\dfrac{\sqrt{2mK}}{qB}\propto\dfrac{\sqrt m}q$ at equal $K$ .

Ratios. Proton $\frac{\sqrt1}1=1$ , deuteron $\frac{\sqrt2}1=\sqrt2$ , $\alpha$ $\frac{\sqrt4}2=1$ .

So $1:\sqrt2:1$ .

(D)

Topics:Motion in magnetic and electric fields

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JEE Main 2022 · 24 Jun · Shift 2, Physics question 39