Electricity - Circuits Flashcards
what is a current
flow of electrical charge
in what direction does current flow in
postie to negative terminal
what is charge
size of current
what is the equation for charge
q = it
what does pd do
push charge around circuit
what is resistance
anything that reduces flow of current, measured in ohms
how do you work out pd from resistance and current
ir
if the current of an ohmic conductor changes, what happens to the resistance
stays the same
give an example of an ohmic conductor
wire, resistor
iv characteristic of a filament lamp
resistance increases w temp so as lamp heats up res increases and eventually current decreases
iv characteristic of a diode
very high current going in ojne way. Graph has horizontal line then strainglt ling up
what precautions can be taken when investigating the resistance of a diode
protective resister
what is the p.d of a series circuit
sum of the pd of the power supply
p.d is shared between the conponents
what is the p.d of a parallel circuit
same in all the components
what is the current of a parallel circuit
add up the currents of all the different components
what is the resistance in a series circuit
the sum of the resistance of all the components added together
what is the resistance of a parallel circuit
the total resistance is less than the smallest resistance if an individual circuit branch because it give the current more directions to go in
what happens to the resistance of an ldr when light intensity increases
resistance decreases
what happens to the resistance of thermistors when light intensity increases
resistance drops
for auto lights when it gets dark
use output pd
