A. The proton is replaced with He2+ ion now at a distance of 3 cm from the bead. What is the magnitude of the force experienced by the helium ion?
B. A parallel plate capacitor has circular plates of diamter 12 cm and is filled with air (dielectric constant k=1). The plates are separated by 7.5 mm. The capacitor has a charge of 330 pC. The capacitance of the capacitor is equal to?
C. What is the voltage on the capacitor?