A conducting sphere is placed within a conducting spherical shell. The conductors are in electrostatic equilibrium. The inner sphere has a radius of $1.50 \mathrm{cm}$ the inner radius of the spherical shell is $2.25 \mathrm{cm},$ and the outer radius of the shell is $2.75 \mathrm{cm}$. If the inner sphere has a charge of $230 \mathrm{nC}$ and the spherical shell has zero net charge, (a) what is the magnitude of the electric field at a point $1.75 \mathrm{cm}$ from the center?
(b) What is the electric field at a point $2.50 \mathrm{cm}$ from the center?
(c) What is the electric field at a point $3.00 \mathrm{cm}$ from the center? [Hint: What must be true about the electric field inside a conductor in electrostatic equilibrium?]