Chapter 26, Problem 45AP

Review. A parallel-plate capacitor consists of square plates of edge length ℓ that are separated by a distance d, where d << ℓ. A potential difference ΔV is maintained between the plates. A material of dielectric constant κ fills half the space between the plates. The dielectric slab is withdrawn from the capacitor as shown in Figure P26.45. (a) Find the capacitance when the left edge of the dielectric is at a distance x from the center of the capacitor. (b) If the dielectric is removed at a constant speed v, what is the current in the circuit as the dielectric is being withdrawn?

Figure P26.45