The kinetic energy of a charge q of mass m in potential is given by,
21mv2=qV
mv=2mqV
Then, the radius of the charge will be,
r=qB2mqV
⇒r∝qm
Hence, the ratio of radius of proton to α-particle,
rαrp=41×12=21.
JEE Main 2019 — Physics Electromagnetism
A proton and an α- particle (with their masses in the ratio of 1:4 and charges in the ratio of 1:2 ) are accelerated from rest through a potential difference V. If a uniform magnetic field (B) is set up perpendicular to their velocities, the ratio of the radii rp:rα of the circular paths described by them will be:
Held on 12 Jan 2019 · Verified 6 Jul 2026.
1:3
1:2
1:2
1:3
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