potential difference and power

What role do electrons play when a bulb is connected to a battery?

They deliver energy from the battery to the bulb

How much energy does each electron take from the battery?

A fixed amount of energy each time it passes through the battery

What happens to an electron after it has done a complete loop around the circuit and re-enters the battery?

It is resupplied with its fixed amount of energy to supply to components

When does a battery have the potential to transfer energy from its chemical store?

When it is not part of a complete circuit

What does an electron do as it passes through a circuit component?

It does work to pass through the component, transferring some or all of its energy

What is the relationship between work done by an electron and its energy?

The work done by an electron is equal to its loss f energy

What is the definition of the emf of a source of electricity

The electrical energy produced per unit charge passing through the source

What two effects does an electric current have when passing through a component with resistance?

A heating effect and a magnetic effect

Give two examples of devices that make use of the magnetic effect of an electrical heater current

Electric motors and loudspeakers

How is work done on a resistive device transferred?

As thermal energy

Why does a resistor becomes hotter hotter when current passes through it?

Charger carriers repeatedly collide with atoms in the device, transferring energy to them, causing the atoms to vibrate more

In an electric motor turning at constant speed, what is the relationship between work done on the motor and energy transferred?

The work done on the motor equals the energy transferred to the load and surroundings, so the kinetic energy of the motor remains constant

Why must electrons be forced through the wires of a spinning motor coil?

Because they must overcome the opposing force on them due to the motors magnetic field

How is work done on a loudspeaker transferred?

As sound energy

Why must electrons be forced through the wires of a vibrating loudspeaker coil?

Because they must overcome the force on them due to the loudspeaker magnet