Two 10cm diameter metal disks separated by a 0.63mm thick piece of pyrex glass are charged to a potential difference of 1000V. Dialectric constant for pyrex is K=4.7. What is the surface charge density on the disks?
parallel-plate capacitor has there fore formula is
C=(ϵ0A)/d putting valuesC=(8.85*10^-12*pi*.05^2)/.00063 =1.1*10^-10F
then Q=CV=1.1*10^-10*1000=1.1*10^-7C as η=Q/Atherefore (1.1*10^-7)/(pi*.05^2) =1.4*10^-5C/m^ our answer hope this helps