As shown in Figure, a particle of charge +Q produces an electric field of magnitude Epart at point P, at distance R from the particle. As in figure b, that same amount of charge is spread uniformly along a circular arc that has radius R and subtends an angle ?. The charge on the arc produces an electric field of magnitude Earc at its center of curvature P. For what value of ? does Earc = 0.50 Epart ?

As shown in Figure, a particle of charge +Q produces an electric field of magnitude Epart at point P, at distance R from the particle. As in figure b, that same amount of charge is spread uniformly along a circular arc that has radius R and subtends an angle ?. The charge on the arc produces an electric field of magnitude Earc at its center of curvature P. For what value of ? does Earc = 0.50 Epart ?