JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
A proton and an \(\alpha\) -particle, having kinetic energies \(K _{ p }\) and \(K _{\alpha},\) respectively, enter into \(a\) magnetic field at right angles. The ratio of the radii of trajectory of proton to that of \(\alpha\) -particle is \(2: 1 .\) The ratio of \(K _{ p }: K _{\alpha}\) is :
- A \(1:8\)
- B \(8:1\)
- C \(1:4\)
- D \(4:1\)
Answer & Solution
Correct Answer
(D) \(4:1\)
Step-by-step Solution
Detailed explanation
\(r =\frac{ mv }{ qB }=\frac{ p }{ qB } \quad \frac{ m _{\alpha}}{ m _{ p }}=4\) \(\frac{ r _{ p }}{ r _{\alpha}}=\frac{ p _{ p }}{ q _{ p }} \frac{ q _{\alpha}}{ p _{\alpha}}=\frac{2}{1}\)…
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