Capacitance

Question 1

Capacitor

Answer 1

A device designed to store charge, formed by two metal plates placed near each other, when the plates are connected to a battery electrons travel to the positive terminal of the battery and electrons are forced away from the negative terminal of the battery to one of the plates so that each plate gains an equal and opposite charge.

Question 2

Capacitance

Answer 2

The charge stored per unit pd, C = Q/V = Aεoεr/d.

Question 3

Energy stored by the capacitor

Answer 3

E = 1/2 QV

Question 4

Capacitor discharging equation

Answer 4

Q = Qo e^-t/RC

Question 5

Capacitor charging equation

Answer 5

Q = Qo (1 - e^-t/RC)

Question 6

Dielectrics

Answer 6

Electrically insulating materials that increase the ability of a parallel-plate capacitor to store charge when a dielectric is placed between the plates of the capacitor.

Question 7

Examples of dielectrics

Answer 7

Polythene and waxed paper.

Question 8

Relative permittivity, εr

Answer 8

The ratio of the charge stored with the dielectric to the charge stored without the dielectric, also known as the dielectric constant, εr = Q/Qo = C/Co.