Electromagnetism

• When a current flows through a wire, it produces a magnetic field around the wire.
• Larger currents produce stronger magnetic fields.
• The magnetic field around a solenoid is stronger than the magnetic field around a straight wire
• The magnetic field is weaker further away from the wire
• A wire is like a bar magnet
• An electromagnet is a solenoid which is wrapped around an Iron core
• The magnetic field is stronger:

  . Closer to the wire

  . If the current is increased
• The magnetic field around a solenoid is strong and uniform ( keeps the same shape all the way through )
• A simple electromagnet is made by coiling wire around an iron nail
• Electromagnets are used in devices such as electric bells, and door locks that can be controlled remotely
• magnetic field: an area surrounding a magnet that can exert a force on magnetic materials.
• To calculate the force on a wire carrying a current at right angles to a magnetic field, use the equation:

  force = magnetic flux density × current × length
• F is force in newtons (N
• • B is magnetic flux density (magnetic field strength) in tesla (T)
• • I is current in amperes - also referred to as amps (A)