Question

12. A plastic sphere of mass 2.1 g has been charged to-3.0 nc What is the magnitude of the vertically-directed electric field that balances the weight of the sphere? 0 78 x 10 N/C 015x106 NC 0 69 x 106 N/C O 2.1 x 106 N/C 13. Aspherical conductor with radius 2.0 mm carries a charge of70 μC what is the electrical (1pom) field strength at a distance of 6.0 mm from the center of the conductor? Let the constant 90 x 10 N.m2c2 o 1.8 x 109 NC 0780 × 109 NC o SS x 109 N/c o 25 x 10 NC 14. A small glass bead has been charged to 1.9 sC. What is the strength of the electric field 20 cm ( po from the center of the bead? Let the constant k-90 10N. m2 o o 8.5 10-7 NC o 4.3 x 101NC O 8.1-10-5 N C @8.5×102 NC

Answer 1

For balance of weight Fg = Fe mg = qE (2.1 times 10^-3) (9.8) = (3 times 10^-9) (E) E = 6.86 times 10^6 N/C almostequalto 6.9 times 10^6 N/C r = 6 mm theta = 7 mu c E = k theta/r^2 = (9 times 10^9) (7 times 10^-6)/(6 times 10^3)^2 E = 1.8 times 10^9 N/C q = 1.9 nc r = 2 cm E = kq/r^2 = (9 times 10^9) (1.9 times 10^-9)/(2 times 10^-2)^2 E = 4.3 times 10^4 N/C