Electrical Circuits
What are the two things an electric current needs to flow?
Complete circuit
Something to push the current around the circuit; e.g. a power supply/cell/battery (a battery is just two or more cells connected end-to-end)
The equation used to calculate the resistance of a component in a circuit is
R= V/I
Where do the electrons and electric current flow?
-Electrons flow from negative to positive
-Electric current flows from positive to negative
We can see the p.d V on the graph is on the _ axis
Name four metals that work well as conductors.
Good conductors: most metals, including copper, silver, gold and steel
We can see the current I on graphs is on the _ axis
Why is the metal is usually surrounded by plastic?
The metal is usually surrounded by plastic so that, if the two wires touch, the electric current cannot pass directly from one to another (a short circuit)
How can u tell the difference between an ohmic resistor with a filament lamp?
The graph for an ohmic resistor is a straight line through the origin while a filament lamp is not.
Name the two types of ammeters and their difference.
An analogue meter has a needle, which moves across a scale; you have to make a judgement of the position of the needle against the scale
A digital meter gives a direct read-out in figures; there is no judgement involved in taking a reading
The resistance of a wire depends on its ?
Length and diameter