A uniform electric field exists in x y plane as shown in Fig. 3.45. Find the potential difference. Between origin O and `A(d,d,0)`.
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Explanation

Here `vec E = E cos theta hat i + E sin theta hat j`
`vec l = vec(OA) = d hat i + d hat j`
`- Delta V = vec E . Vec l`
=`E d cos theta + E d sin theta = E d(cos theta + sin theta)`
`:. -(V_A - V_0) = E d (cos theta + sin theta)`
or `V_0 - V_A = E d (cos theta + sin theta)`.