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A disc having uniform surface charge den...

A disc having uniform surface charge density in upper part `+rho` and `-rho` in lower half placed on rough horizontal surface as shown in figure. A uniform electric field is set up as shown if mass of disc is M and its radius is R as well sufficient friction is present to prevent slipping. The acceleration of disc is

A

`(8)/(9)(rhoR^(2)E_(0))/(M)`

B

`(9)/(8)(rhoR^(2)E_(0))/(M)`

C

`(4)/(3)(rhoR^(2)E_(0))/(M)`

D

`(3)/(4)(rhoR^(2)E_(0))/(M)`

Text Solution

Verified by Experts

The correct Answer is:
A
Dipole moment `((sigmapiR^(2))/(2)) (2.(4R)/(3pi))`

`(4R^(3)sigma)/(3)`
`f_(r ) = Ma`
`(4R^(3)sigma)/(3)E - f_(r )R = (MR^(2))/(2)alpha`
`alpha = (a)/(R )`
For pure rolling
`a=(8)/(9)(rhoER^(2))/(M)`
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