Two plastic spheres The figure shows two thin plastic spherical shells (shown in

Question

Two plastic spheres
The figure shows two thin plastic spherical shells (shown in cross section) that are uniformly charged. The center of the larger sphere is at < 0, 0, 0 >; it has a radius of 12 cm and a uniform positive charge of 4 multiplied by 10-9 C. The center of the smaller sphere is at < 25, 0, 0 > cm; it has a radius of 3 cm and a uniform negative charge of -2 multiplied by 10-9 C.


a) What is the electric field 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.
? N/C in vector notation
(b) What is the electric field at location B (15 cm above the center of the small sphere)? Again, neglect the small contribution of the polarized molecules in the plastic, because the shells are very thin and don't contain much matter.
? N/C in vector notation
(c) What is the force on an electron placed at location B?
? N (in vector notation)

Explanation / Answer

a) The electric field experienced by the big sphere is 0
The electric field caused by the smaller sphere is
E_s= 2nc*k/(.25-.06)^2*<1,0,0>
E_s= <4.98 N/C,0,0>
b) Now we can include the large sphere .
E_L= 4nC*k/r^2*(unit vector), r=(25/100)^2+(15/100)^2, unit vector= <.25/.085, .15/.085,0>

E_L= 4nC*k/(25/100)^2+(15/100)^2 * <.25/.085, .15/.085,0>

E_L= <362.77 N/C, 217.66 N/C,0>

E_s= 2nC*k/(.15)^2*<0,-1>

E_s= <0, -799.11 N/C,0>

E_tot= E_L+E_s= <362.77 N/C, 217.66 N/C-799.11,0>

E_tot=<362.77 N/C, -581.45 N/C,0>

c) F=q_e*E_tot, q_e= -1.6*10^-19 C

F=-1.6*10^-19<362.77 N/C, -581.45 N/C,0>

F=<-5.804*10^-17N,9.303*10^-17N,0>

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.