JEE Mains · Physics · STD 12 - 1. Electric charges and fields
A body having specific charge \(8\,\mu {C} / {g}\) is resting on a frictionless plane at a distance \(10\, {cm}\) from the wall (as shown in the figure). It starts moving towards the wall when a uniform electric field of \(100 \,{V} / {m}\) is applied horizontally toward the wall. If the collision of the body with the wall is perfectly elastic, then the time period of the motion will be \(....\, S.\)
- A \(1\)
- B \(5\)
- C \(7\)
- D \(8\)
Answer & Solution
Correct Answer
(A) \(1\)
Step-by-step Solution
Detailed explanation
\(F=m a\) \(q E=m a\) \(a=\frac{q E}{m}\) Now \(d=\frac{1}{2} a t^{2}\) \(t=\sqrt{\frac{2 d}{a}}\) \(t=\sqrt{\frac{2 d}{\left(\frac{q E}{m}\right)}}\) \(t=\frac{2 \times 0.1}{\left(\frac{8 \times 10^{-6}}{m 10^{-3}}\right) \times 100}=\frac{1}{2}\)
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