In part a of the figure an electron is shot directly away fr

In part (a) of the figure an electron is shot directly away from a uniformly charged plastic sheet, at speed v_s = 2.80 Times 10^5 m/s. The sheet is nonconducting, flat, and very large. Part (b) of the figure gives the electron\'s vertical velocity component v versus time t until the return to the launch point. What is the sheet\'s surface charge density?

Solution

Electric field due a large sheet is given by Charge density / 2₀

Therefore, the force exerted by the sheet on the charge = Q*ChargeDensity / 2₀

Electron\'s speed drops to zero in 8 seconds [As per the graph]

Deceleration = Force/ mass

further, V = at; that is 2.8 x 10^5/ 8 = Q*ChargeDensity / 2*m*₀

Hence, 2.8 x 10^5/ 8 = 1.6 x 10^-24 * X / 2 * 9.1 x 8.854

That is, X = 35.25 x 10^29 C/m^2