Question

1,The same voltage is applied between the plates of two different capacitors. When used with capacitor A, this voltage causes the capacitor to store 15 μC of charge and 3.4 x 10-5 J of energy. When used with capacitor B, which has a capacitance of 7.9 μF, this voltage causes the capacitor to store a charge that has a magnitude of qB. Determine qB.

2,The membrane that surrounds a certain type of living cell has a surface area of 6.0 x 10-9 m2 and a thickness of 1.2 x 10-8 m. Assume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 5.8. (a) The potential on the outer surface of the membrane is +61.9 mV greater than that on the inside surface. How much charge resides on the outer surface? (b) If the charge in part (a) is due to K+ ions (charge +e), how many such ions are present on the outer surface?

3,Three point charges, -4.5 x 10-9 C, -9.9 x 10-9 C, and +7.9 x 10-9 C, are fixed at different positions on a circle. The total electric potential at the center of the circle is -2100 V. What is the radius of the circle?

Answer 1