Circuits, resistance current and potential difference

which way does conventional current flow in a circuit?

it flows from the positive to the negative terminal

which line in the cell is the negative terminal and which one is the positive terminal?

the longer line in a cell is the positive terminal and the shorter line is the negative terminal

which way do electrons flow in a circuit?

electrons are negatively charged so flow around from the positive to negative terminal

what's an electric circuit?

a closed loop that contains a power source such as a cell

what is a closed switch?

a component that allows current to continue flowing round the circuit

what is a battery?

two more cells connected in series/provides voltage for the circuit

what is a cell?

serves same function as battery

what does an open switch do?

disrupts the circuit's flow of current

what is current measured in?

it is measured in amperes

what is current?

the flow of electrons around a circuit

what is voltage measured in?

volts

what is resistance measured in?

Ohms (Ω)

what is resistance?

a measure of the opposition to current flow in a circuit

what is a filament lamp?

light bulbs which contain very thin metal filament

Explain the shape of a filament lamp graph

- as current flows through filament wire wire heats up gets so hot it emits light
- heat massively increases resistance so curve gets less steep

what does the filament graph lamp show?

it shows less current can flow per unit of V at these higher voltages, because temperature and resistance are so high

what does a diode do?

only allows current flow in one direction

How does a diode allow current flow in one direction?

by having a really high resistance in the opposite direction and it only allows current when PD is positive

what is ohm's law?

the law that states that as long as the resistance stays constant as you increase the voltage the current should increase proportionally

what is voltage ?

Voltage is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop/ or the force driving the flow of electrons/ a measure of how much energy is transferred from the electrons to the components

as temperature in a circuit increases... also increases

resistance

equation for ohm's law

V=IR

why do we get straight lines in circuits that only contain wires and normal resistors/ ohmic conductors?

because the resistance stays constant

larger resistance= ... steep line

less

smaller resistance= ... steep line

more

why does a wire heat up as current passes through it

because the moving electrons collide with the atoms in the wire, transferring their kinetic energy into thermal energy, which manifests as heat

why does resistance increase as wire length increases

• Longer wires have more resistance because electrons collide more with the atoms in the wire as they travel through. The longer the wire, the more collisions happen, which opposes the flow of current.

• In a shorter wire, there’s less material for the electrons to collide with, so the resistance is lower.

How does increasing the temperature of a metal conductor affect its resistance?

increasing the temperature increases resistance as the electrons have more kinetic energy and so collide more with the metal atoms opposing the flow of current