A hollow conducting spherical shell has radii of 0.80 m and 1.20 m, as shown in the figure. The sphere carries a net excess charge of -500 nC. A point charge of +300 nC is present at the center. (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C) The radial component of the electric field at a point that is 1.50 m from the center is closest to A) +1200 N/C. B) +2000 N/C. C) -800 N/C. D) -1600 N/C. E) -2000 N/C.

Question

Quizplus · Accepted Answer

Inside a hollow conducting sphere, the electric field is zero due to charge redistribution. Therefore, the electric field at a distance of 1.5 m from the center is due to the point charge of +300 nC only. Using Coulomb's law, we can find the electric field:
$$E=\frac{kq}{r^2}=\frac{8.99	imes 10^9\cdot 300	imes 10^{-9}}{(1.5)^2}=800	ext{ N/C}$$
However, the electric field points towards the negative excess charge on the conducting sphere, so the direction is opposite to that of the point charge. Therefore, the final answer is -800 N/C, which is closest to choice C.

A Hollow Conducting Spherical Shell Has Radii of 0