# Mahi Tuatahi

The battery is 12V.

{width=30%}

1. When switched on, how many joules of energy does the cell supply to each coulomb of charge that flows out of the cell? (A)

{width=30%}

1. When the cell is switched on, the resistance of the lamp is $9\Omega$. Calculate the current flowing through the lamp. (A)
2. State the meaning of the term resistance in terms of electron flow. (A)

# Magnetic Fields

Magnetic fields can be found in two places:

• Around magnetic objects
• Around current carrying wires

{width=75%}

{width=50%}

## Right Hand Grip Rule 1

• Used to find the direction of the current or magnetic field when you know the other.
• This version of the right hand grip rule only applies to current carrying wires!

{width=40%}

## Right Hand Grip Rule 2

• Used to find the direction of the magnetic field in a coil of wire.

{width=50%}

## Magnetic Elements

{width=75%}

### Ferromagnetism

• Includes Co, Fe and Ni
• Permanent magnets
• Were exposed to a strong external magnetic field and retained the field after being removed from it

### Paramagnetism

• Includes Na, Mg, Ca etc.
• Can form a weak internal magnetic field when exposed to an external magnetic field
• Feel a small attractive force

### Diamagnetism

• Includes Cu, Si, N, C etc.
• Can form a weak internal magnetic field when exposed to an external magnetic field
• Feel a small repulsive force

{width=50%}