Capacitors ch.7
Capacitance def.?
- the capacitance of 1 farad (F) is 1 coulomb of charge is stored for a p.d. of 1 V between
the plates
Type of electric field formed between the plates of a capacitor?
- uniform
How to increase the charge stored on plates?
- insert dielectric in between plates
→ these are electrically insulating materials, but a good supporters of electrostatic fields
Examples of dielectric materials?
- polyethylene
- waxed paper
Describe the dielectric action (i.e. what happens when a dielectric is inserted between
the two plates)?
- each molecule of the dielectric becomes polarised ← the electrons in the molecules are
slightly pulled towards the positive plate ⇒ opposite ends are slightly negative and positive
relative to each other
→ dielectric increases charge stored for any given p.d. ⇒
increases
Permittivity def. and symbol?
- a property of dielectrics
- the measure of the ability to store an electric field in a material
, Relative permittivity def.?
Describe the action of a simple polar molecule that rotates in the presence of an
electric field (in an AC circuit)?
→ only focus on electronic polarisation
Relative permittivity synonym?
- dielectric constant
Factors affecting capacitance?
Capacitance def.?
- the capacitance of 1 farad (F) is 1 coulomb of charge is stored for a p.d. of 1 V between
the plates
Type of electric field formed between the plates of a capacitor?
- uniform
How to increase the charge stored on plates?
- insert dielectric in between plates
→ these are electrically insulating materials, but a good supporters of electrostatic fields
Examples of dielectric materials?
- polyethylene
- waxed paper
Describe the dielectric action (i.e. what happens when a dielectric is inserted between
the two plates)?
- each molecule of the dielectric becomes polarised ← the electrons in the molecules are
slightly pulled towards the positive plate ⇒ opposite ends are slightly negative and positive
relative to each other
→ dielectric increases charge stored for any given p.d. ⇒
increases
Permittivity def. and symbol?
- a property of dielectrics
- the measure of the ability to store an electric field in a material
, Relative permittivity def.?
Describe the action of a simple polar molecule that rotates in the presence of an
electric field (in an AC circuit)?
→ only focus on electronic polarisation
Relative permittivity synonym?
- dielectric constant
Factors affecting capacitance?
