Part a of the figure shows two charged particles fixed in pl

Part (a) of the figure shows two charged particles fixed in place on an x axis with separation L. The ratio q_1/q_2 of their charge magnitudes is 4.00. Part (b) of the figure shows the x component Enet x of their net electric field along the x axis just to the right of particle 2. The x axis scale is set by x_s = 32.4 cm. (a) At what value of x > 0 is Enetx maximum? (b) If particle 2 has charge -5e, what is the value of that maximum? Assume e = 1.602 x 10^-19 C.

Solution

From the plot the maximum value postive value of electric field is at x = 97.2 cm

when q1/ q2 = 4 and q2 =-5e then q1 = 20e

            Eelectric field due to q1 at 97.2cm = k q1 / r^2 = + k * 20 * 1.6 *10^-19 / 0.972^2 = 3.041*10^-7N/c

            Eelectric field due to q2 at 97.2cm = k q2 / r^2 =   - k * 5 * 1.6 *10^-19 / 0.972^2 = -7.603*10^-8N/c

       Enet = Eq1-Eq2 = 30.41 *10^-8 N/C - 7.603*10^-8 N/C

   = 2.2 807 *10^ -8 N/C