A capacitor is constructed from two square plates of sides l and separation d. Charges and are placed on the plates, and the power supply is then removed. A material of dielectric constant κ is inserted a distance x into the capacitor, as in Figure P25.49 (page 690). Assume d is much smaller than x.
a) Find the equivalent capacitance of the device.
b) Calculate the energy stored in the capacitor.
c) Find the direction and magnitude of the force exerted on the dielectric.
d) Obtain a numerical value of the force when , assuming that , , the dielectric is glass , and the capacitor was charged to before the dielectric was inserted.
Suggestion: The system can be considered as two capacitors connected in parallel.
