define// capacitance

Question 1

briefly outline how charge is built up on a capacitor

Answer 1

A capacitor is made up of two conducting plates separated by a gap
when connected to a power source, negative and positive charge build up in opposite plates creating a uniform electric field

Question 2

define capacitance

Answer 2

C=Q/V
the amount of charge per unit potential difference stored by a capacitor

Question 3

Define the term dielectric

Answer 3

An electrical insulator that can be polarised by an applied electric field

Question 4

Define the term dielectric constant

Answer 4

the ratio of the permittivity of a material to the permittivity of free space

also known as relative permittivity

Question 5

Why does diametric increase the capacitance of a capacitor

Answer 5

the molecules of the dielectric have their own electric field opposing the applied electric field of the capacitor, the larger the permittivity the larger the field
This reduces pverral electric field which reduces the potential difference thus increasing capacitance

Question 6

Define time constant

Answer 6

The time taken for the charge, current or voltage to decrease to 37% of its original value or increase by 63% of maximum value

Question 7

Define time to halve

Answer 7

Time taken to the charge, current or voltage of a discharging capacitor to reach half its original value.