Find the electric field at centre of semicircular ring shown in figure .
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Answer

`(-kq)/(piR^(2)) hat(i)`

Explanation

`E_("net")=2underset(0)overset(pi//2)(int)dE sin theta`
`rArr 2underset(0)overset(pi//2)(int) ((Kq)/((piR//2))xxRd theta)/R^(2)xxsin theta=(4Kq)/(piR^(2))`
`rArr vec(E)=((4Kq)/(piR^(2)))(-hat(i))N//C`