Define the term electric potential due to a point charge .
Calculate the electric potential at the centre of a square , of side `sqrt2` m , having charges `100 mu C , -50 mu C , 20 mu C ` and `-60 mu C ` at the four corners of this square .

Explanation

As shown in Fig distance of centre point O from the corners of square i.e.,
`r = AO = BO = CO = DO = (1)/(2) sqrt((sqrt2)^(2) + (sqrt2)^(2)) = 1m`
`therefore` Net electric potential at point O
`V = (1)/(4 pi in_(0) r) [q_(1) + q_(2) + q_(3) + q_(4)]`
`= (9 xx 10^(-9))/(1) [ 100 - 50 + 20 - 60] mu C = (9 xx 10^(9) xx 10 xx 10^(-6))/(1) = 9 xx 10^(4) V`