Chapter 19: Q35P (page 797)

Which of the following statements about the discharging of a capacitor through a light bulb are correct? Choose all that are true. (1) The fringe field of the capacitor decreases as the charge on the capacitor plates decreases. (2) Electrons flow across the gap between the plates of the capacitor, thus reducing the charge on the capacitor. (3) The electric field at a location inside the wire is due to charge on the surface of the wires and charge on the plates of the capacitor. (4) Electrons in the wires flow away from the negative plate toward the positive plate, reducing the charge on the plates.

Short Answer

Expert verified

The correct statements are:

(1) The fringe field of the capacitor decreases as the charge on the capacitor plates decreases.

(4) Electrons in the wires flow away from the negative plate toward the positive plate, reducing the charge on the plates.

Step by step solution

Given data

The following statements are provided:

(1) The fringe field of the capacitor decreases as the charge on the capacitor plates decreases.

(2) Electrons flow across the gap between the plates of the capacitor, thus reducing the charge on the capacitor.

(3) The electric field at a location inside the wire is due to charge on the surface of the wires and charge on the plates of the capacitor.

(4) Electrons in the wires flow away from the negative plate toward the positive plate, reducing the charge on the plates.

Discharging of a capacitor

While a capacitor discharges, electrons on the negative plate are forced across the circuit by the fringe field of the capacitor. The electrons move to the positive terminal thus reducing the charge on both plates and hence reducing the fringe field. This continues until the capacitor is fully discharged.

Determination of whether the provided statements are true or false

During discharging of a capacitor, electrons move from the negative to the positive plate thus reducing the charge accumulation in both plates and hence reducing the fringe field. Thus, statement (1) is true.

No charge flows across the gap between the two plates of a capacitor. Thus, statement (2) is false.

While discharging, the only field in the wires is the field created due to the charge difference between the plates of a capacitor. Thus, statement (3) is false.

Electrons do flow from the negative plate to the positive plate while discharging, thus reducing the charge on each plate. Hence, statement (4) is true.