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CUET · PHYSICS · PYQ PAPER 2025

A proton, a deuteron and an alpha particle have the same kinetic energy and move in a uniform magnetic field perpendicular to their direction of motion. The ratio of the radii of their circular paths is :

  1. A \( 1 : \sqrt{2} : 2 \)
  2. B \( 1 : 2 : \sqrt{2} \)
  3. C \( 1 : \sqrt{2} : 4 \)
  4. D \( 1 : \sqrt{2} : 1 \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( 1 : \sqrt{2} : 1 \)

Step-by-step Solution

Detailed explanation

\( r = \frac{\sqrt{2Km}}{qB} \) \( r \propto \frac{\sqrt{m}}{q} \) \( r_p : r_d : r_\alpha = \frac{\sqrt{m_p}}{q_p} : \frac{\sqrt{m_d}}{q_d} : \frac{\sqrt{m_\alpha}}{q_\alpha} \) \( r_p : r_d : r_\alpha = \frac{\sqrt{m}}{e} : \frac{\sqrt{2m}}{e} : \frac{\sqrt{4m}}{2e} \)…