Capacitance (6)

Question 1

Electric current

Answer 1

the rate of flow of electric charge. Measured in amperes.

Question 2

Electric power

Answer 2

the rate of doing electrical work.

Question 3

Capacitance

Answer 3

the capacitance of a capacitor is the ability of the capacitor to store charge per unit potential difference.

Question 4

Farad

Answer 4

the unit of capacitance, where 1F is equal to 1CV-1 (one coulomb per volt).

Question 5

Permittivity

Answer 5

the permittivity of a material is the resistance of the material to an electric field passing through it.

Question 6

Dielectric constant

Answer 6

another term for the relative permittivity of an insulating material. It describes the relative resistance of the material to the propagation of electric field through it and describes the absolute permittivity of the material in terms of multiples of the permittivity of free space, ε_r ε_0.

Question 7

Dielectric material

Answer 7

an insulating material where the molecules that make up the material can be polarised inside an electric field. Electric charges do not move through the material, but the polar molecules align themselves with the field.

Question 8

Half-life of a capacitor

Answer 8

the time taken for the charge stored on the capacitor (or the current or the voltage) to halve.

Question 9

Time constant, RC

Answer 9

the time for the charge stored on the capacitor to drop to 37% of the initial value, Q_0.
t_(1/2)=0.693RC.