P5 physics revision

1) 2 insulating materials rubbed together, electrons are scraped off one and dumped on the other.

2) this leaves a +tive static charge on one and a -tive static charge on the other.

3)which way that the elctrons are moved depends on the two materials involved

4) electrically charged objects attract small objects placed near them.

5) the classic example are polythene and acetate rods being rubbed with a cloth duster.

1) current will only flow through a componnent if theres a voltage across that componnent

2)voltage is the driving force that pushes the current around

3) resistance is anything is anything in the circuit that slows the flow down

4) theres a balance: the voltage is trying to push the current round the circuit, and the resistance is opposing it- the relative sizes of the voltage and resistance decide how big the current will be.

if you increase the voltage- then more current will flow

if you increase the resistance- then less current will flow

Calculating Resistance

resistance = potential difference/ current