Bob connects a capacitor to a battery until the capacitor is fully charged, and
ID: 2214671 • Letter: B
Question
Bob connects a capacitor to a battery until the capacitor is fully charged, and then disconnects the capacitor from the battery. Jim then slides a neutral DIELECTRIC between the plates of the capacitor.
Do the following increase, decrease or stay the same? PLEASE EXPLAIN EACH ANSWER.
1. Charge on capacitor plate. Increase, decrease or stay the same? PLEASE EXPLAIN
2. Net electric field between the plates. Increase, decrease or stay the same? PLEASE EXPLAIN
3. Voltage difference between the plates. Increase, decrease or stay the same? PLEASE EXPLAIN
4. Capacitance. Increase, decrease or stay the same? PLEASE EXPLAIN
5. Energy stored by the capacitor. Increase, decrease or stay the same? PLEASE EXPLAIN
Explanation / Answer
1. Charge remains constant, because there is no battery to provide additional charge to the capacitor. 2. electric field = V/d (V = voltage difference,d = distance between plates ) V/d = Q/(Cd) . Q is constant and C increases because of the introduction of dielectric. Hence net electric field decreases. 3.Voltage difference decreases, because V = Q/C. C = EoEr*A/d ; With the introduction of dielectric, Capacitance increases, hence voltage decreases . 4. Capacitance increases. 5. E = 0.5*(Q^2/C). Since Q = constant and C increases, E decreases.