Physics 1.9

Magnetic field

Magnet feels a force

Magnetic field lines

Visualise magnetic fields

Direction of magnetic field lines

North to south

Closer magnetic field lines

Stronger magnetic field

The motor effect

A current carrying wire that is inside a magnetic field causes movement

Flemings left hand rule - Thumb

Movement

Flemings left hand - First finger

Field

Flemings left hand - Second finger

Current

Increase DC motor force

• Size of current

• Strength of field

• Number of turns in wire

Strength of magnetic field

Density of magnetic field lines (Measured in T)

Electric motors changing energy

Electrical to Kinetic

F in F=BIL

Force on wire (N)

B in F=BIL

Magnetic field strength (B)

I in F=BIL

Current (A)

L in F=BIL

Length of wire (M)

Electromagnetic induction

Conducting wire moves inside a magnetic field making a current

Direction of induced current

Direction of magnetic field and direction of rotation of the coil

Flemings right hand - Thumb

Movement

Flemings right hand - First finger

Field

Flemings right hand - second finger

Current

Size of induced current

• Rate of rotation

• Number of turns

• Strength of magnetic field

Electricity transmitted across the country

High voltage, low current

Primary coil in transformer

Alternating current

Secondary coil in transformer

Changing magnetic field

Iron core in transformer

Link to transfer magnetic field

V1

Voltage in primary

V2

Voltage in secondary coil

N1

Turns in primary coil

N2

Turns in secondary coil