The resistivityr of glass, silver and copper are 10'\

The resistivity of glass, silver and copper are 10-12, 1.59x10-s and 1.68x10-s Qm respectively. (a) If free charges are embedded in a piece of glass how long would it take for the charge to flow to the surface? (b) How thick should silver coating be to operate at a frequency of 1010 HzO (c) Find the wavelength and propagation speed in copper for radio waves at 1 MHz?