Question $2$

$5$ Points

The electric field just outside the surface of a hollow conducting sphere of radius $20$ cm has a magnitude of $500$ N$/$C and is directed outward. An unknown charge Q is introduced into the center of the sphere and it is noted that the electric field is still directed outward but has decreased to $100$ N$/$C$.$ What is the magnitude of the charge Q$?$

$1\mathrm{.}5$ nC

$1\mathrm{.}8$ nC

$1\mathrm{.}3$ nC

$1\mathrm{.}1$ nC

$2\mathrm{.}7$ nC