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An electron falls from rest through a ve...

An electron falls from rest through a vertical distance h in a uniform and vertically upward directed electric field E. The direction of electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in it through the same vertical distance h. The time of fall of the electron, in comparison to the time of fall of the proton is

A

equal

B

smaller

C

10 times greater

D

5 times greater

Text Solution

Verified by Experts

The correct Answer is:
B
Acceleration `a=F/m =(qE)/m`
In equation of motion `S =v_(0)t + 1/2at^(2), v_(0)=b`
`therefore S =1/2 xx (qE)/m t^(2)`
`therefore` In `t^(2) =(2sm)/(qE), 2s,q` and E are equal
`therefore t=sqrt((25m)/(qE))`
`therefore t prop sqrt(m)` Mass of proton is greater than mass of electron hence electron will take less time.
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