Electromagnetism

• What phenomenon does electromagnetism describe?

  Electric currents produce magnetic fields
• How does an electric current affect a wire?

  It produces a magnetic field around the wire
• What shape do the magnetic field lines take around a wire?

  Concentric circles around the wire
• Where is the magnetic field strongest around a wire?

  Closest to the wire
• What determines the direction of the magnetic field around a wire?

  The direction of the electric current
• How can you remember the direction of the magnetic field using your hand?

  Use the right hand rule
• What does curling your fingers represent in the right hand rule?

  The direction of the magnetic field
• What direction does the magnetic field go for current flowing upwards?

  Anti-clockwise
• What happens to the magnetic field when current flows in the opposite direction?

  The magnetic field direction reverses
• What shape is formed when two wires are joined together with current flowing through them?

  A flat circular coil
• How do the magnetic fields of a coil interact?

  They combine to form a single magnetic field
• What is a solenoid?

  A coil of wire with many turns
• What is the magnetic field like inside a solenoid?

  Strong and uniform
• How does the magnetic field outside a solenoid compare to that of a bar magnet?

  It resembles the field of a bar magnet
• What do we call a magnet created by electricity?

  Electromagnet
• What happens to an electromagnet when the current is turned off?

  The magnetic field disappears
• How can you reverse the direction of an electromagnet's magnetic field?

  By reversing the current direction
• What happens to the magnetic field lines when the current direction is flipped?

  The direction of the field lines flips
• What is one way to increase the strength of an electromagnet?

  Increase the current flowing through it
• How does increasing the number of turns in a coil affect its strength?

  It increases the strength of the electromagnet
• What happens if you decrease the length of the coil while keeping the number of turns the same?

  The strength of the electromagnet increases
• Why does adding an iron core to a solenoid increase its strength?

  Iron becomes an induced magnet when current flows
• What happens to the iron core when the current is turned off?

  It loses its magnetic field
• What are the four ways to increase the strength of an electromagnet?

  • Increase the current
  • Increase the number of turns in the coil
  • Decrease the length of the coil
  • Add an iron core
• What is the motor effect?

  A current carrying wire in a magnetic field experiences a force
• How does a current carrying wire interact with a magnetic field?

  It experiences a force that pushes it out of the field
• What angle must the wire be at to experience the full force?

  90 degrees to the magnetic field
• What happens if the wire is at a slight angle to the magnetic field?

  It will feel slightly less force
• What is the result if the wire runs in the same direction as the magnetic field?

  It would feel no force at all
• What two directions do we need to find the direction of the force?

  The direction of the magnetic field and the current
• What is Fleming's left-hand rule used for?

  To determine the direction of the force on the wire
• How do you position your fingers according to Fleming's left-hand rule?

  Thumb up, first finger forward, second finger out
• In Fleming's left-hand rule, what does the first finger represent?

  The direction of the magnetic field
• In Fleming's left-hand rule, what does the second finger represent?

  The direction of the current
• What does the thumb represent in Fleming's left-hand rule?

  The direction of the force felt by the wire
• What happens when a current flows through the metal rail between the poles of a horseshoe magnet?

  It experiences a force due to magnetic interaction
• How do you determine the direction of the force in the metal rail scenario?

  Use Fleming's left-hand rule again
• What is the orientation of the magnetic field in the metal rail scenario?

  Pointing downwards from north to south
• How is the current flowing through the rail oriented in the metal rail scenario?

  Towards us
• What is the equation to calculate the strength of the force?

  $F =$$BIL$