A solid sphere of radius R | Electrostatics | JEE-MAIN 2020

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JEE MAIN 2020

05-09-2020 S1

Question

A solid sphere of radius R carries a charge Q + q distributed uniformly over its volume. A very small point like piece of it of mass m gets detached from the bottom of the sphere and falls down vertically under gravity. This piece carries charge q. If it acquires a speed v when it has fallen through a vertical height y (see figure), then : (assume the remaining portion to be spherical).

Select the correct option:

A

$v^2=y\left[\frac{q Q}{4 \pi \varepsilon_0 R(R+y) m}+g\right]$

B

$v^2=2 y\left[\frac{q Q R}{4 \pi \varepsilon_0(R+y)^3 m}+g\right]$

C

$v^2=y\left[\frac{q Q}{4 \pi \varepsilon_0 R^2 y m}+g\right]$

D

$v^2=2 y\left[\frac{q Q}{4 \pi \varepsilon_0 R(R+y) m}+g\right]$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

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