Question

A metal wire is bent into a circle of 10 cm .It is given a charge of 20mu C which spreads on it uniformly . The electric potential at its centre is (a) 1.8*10^7 V (b) 2.2*10^7V (c) 2.6*10^7V (d) 3*10^7V

Answer 1

The potential at the center of the circular wire is simply,

 V = kq/r
Where, k = 9 × 10 Nm^2/C^2
q = 20 × 10^-6 C
r = 10 cm = 0.1 m
Therefore, V = (9 × 10^9 )( 20 × 10^-6 )/(0.1) = 1.8 × 10^6 V

and if charge is 200 micro coulamb then answer will be 1.8 x 10^7 V ,1st option



i hope it will help you
regards

Answer 2

here radius = 10cm =10 × 10^-2m
charge = 20mu C =20×10^-6 C
we know V = k ×q/r
k= 9×10^9
so V = (9×10 ^9 ×20×10^-6 )/10 × 10^-2= 1.8×10^6
but here answer is not given in the option.