Two thin plastic spherical shells (shown in cross section in the figure below) a
ID: 1657106 • Letter: T
Question
Two thin plastic spherical shells (shown in cross section in the figure below) are uniformly charged. The center of the larger sphere is at (0, 0); it has a radius of 12 cm and a uniform positive charge of +8 × 10-9 C. The center of the smaller sphere is at (21 cm, 0); it has a radius of 3 cm and a uniform negative charge of -6 x 10-9 C. (a) What are the components EA,x and EA,y of the electric field E at location A (6 cm to the right of the center of the large sphere)? Neglect the small contribution of the polarized molecules in the plastic, because the shells are very thin and don't contain much matter. (Indicate the direction with the sign of your answer.) A A,y N/C (b) What are the components EB,x and EB,y of the electric field at location B (15 cm above the center of the small sphere)? Neglect the small contribution of the polarized molecules in the plastic, because the shells are very thin and don't contain much matter. (Indicate the direction with the sign of your answer.) Eg,x= -502.69 EB,y= 578.39 X N/C × N/C (c) What are the components Fx and Fy of the force on an electron placed at location B? (Indicate the direction with the sign of your answer.)Explanation / Answer
given two thin plastic charges shells
larger shell, Q = 8*10^-9 C, at (0,0), R = 12 cm
smaller shell, q = -6*10^-9 C, at (21,0), r = 3 cm
a. Ey = 0 at A ( from symmetry)
Ex = kq/(0.21 - 0.06)^2 [ because from gauss lae, Q will not contribute to this electric field]
Ex = 8.98*10^9*(-6*10^-9)/(0.15^2) = 2394.66 V/m ( towards the right )
b. Ex at B = Ex due to large sphere ( smaller sphere will just have y component)
Ex = kQ*0.21/(0.21^2 + 0.15^2)^3/2 = 8.98*10^9*8*10^-9*0.21/0.36^3 = 323.3539 V/m
Ey = kQ*0.15/(0.21^2 + 0.15^2)^3/2 + kq/0.15^2 = -2163.69 V/m
c. For an electron placed at B, e = -1.6*10^-19 C
so, Fx = e*Ex = -517.36624*10^-19 N
Fy = e*Ey = 3461.904 * 10^-19 N
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