A spherical conducting shell has an interiour radius of 18.0 cm and an outer radius of 21.0 cm. The shell carries a net charge of -2.4 microcoulombs. A point charge of charge +6.4 microcoulombs is placed at the center of the spherical shell.
i. calculate the amount of charge on the INSIDE of the conducting shell.
ii. Use Gauss's law to find th electric field 12.0 cm from the center of the system.