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A thin semi-circular ring of radius r ha...

A thin semi-circular ring of radius r has a positive charge q distributed uniformly over it. The net field `vecE` at the centre O is

A

`q/(2 pi^2 varepsilon_0r^2) hat j`

B

`-q/(2 pi^2 varepsilon_0r^2) hat j`

C

`q/(2 pi^2 varepsilon_0r^2) hat j`

D

`-q/(2 pi^2 varepsilon_0r^2) hat j`

Text Solution

Verified by Experts

The correct Answer is:
D
`vec E= ((1klambda)/r) (-hat j) rArr vec E = (lambda)/(2 pi varepsilon_(r) (-hatj)`
`lambda = q/(pir) rArr vec E = q/(2 pi^2 varepsilon_0 r^2) (- hat j)`.
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