electromagnetism

• What is electromagnetism caused by?


  Magnetic fields around electric currents
• How do magnetic fields interact with nearby magnets?


  They can cause forces that make motors spin and loudspeakers produce sound
• What is a solenoid?


  • A straight coil of wire
  • Can carry an electric current
  • Creates a magnetic field
• What happens when a current flows in a wire?


  It creates a circular magnetic field around the wire
• How does the strength of the magnetic field change with distance from the wire?


  The strength is greater closer to the wire
• What is the effect of increasing the current on the magnetic field strength?


  The magnetic field strength increases
• What is the shape of the magnetic field created by a solenoid?


  • Similar to the field of a bar magnet
  • Strong and uniform inside the solenoid
  • Created by the addition of small magnetic fields from each coil
• What is an electromagnet?


  A solenoid with an iron core
• How does an iron core affect a solenoid's magnetic field?


  It increases the magnetic field strength
• What is a simple way to create an electromagnet?


  By coiling wire around an iron nail
• What are some common uses of electromagnets?


  • Electric bells
  • Remote-controlled door locks
  • Various electronic devices
• What is the primary cause of electromagnetism?


  Magnetic fields around electric currents
• How can magnetic fields affect nearby magnets?


  They can cause forces that make motors spin and loudspeakers produce sound
• What is the motor effect?


  • A force exerted on a wire carrying a current in a magnetic field
  • Occurs when the current and magnetic field are not parallel
• What happens to the force on a wire in a magnetic field when the current increases?


  The force increases
• What happens to the force on a wire in a magnetic field when the strength of the magnetic field increases?


  The force increases
• When is the force on a wire in a magnetic field greatest?


  When the direction of the current is 90° to the direction of the magnetic field
• What is the condition for no motor effect to occur?


  When the current and magnetic field are parallel to each other
• How can the direction of the motor effect force be determined?

  Using Fleming’s left hand rule
• What does Fleming's left hand rule indicate?


  • Thumb: direction of the motor effect force
  • Forefinger: direction of the magnetic field (north to south)
  • Second finger: direction of the current (positive to negative)
• If the forefinger points left to right and the second finger points down, in which direction will the force act?


  Towards you
• What are the components of the motor effect as described by Fleming's left hand rule?


  • Thumb: force direction
  • Forefinger: magnetic field direction
  • Second finger: current direction
• What are permanent magnets?


  Permanent magnets are always magnetic and produce their own magnetic field.
• How do induced magnets behave?


  Induced magnets become magnetic in a magnetic field and lose magnetism when the field is removed.
• What is a magnetic field?


  A magnetic field is the region around a magnet where a magnetic force is exerted.
• What do the direction of magnetic field lines indicate?


  The direction of magnetic field lines shows the direction of the force on a north pole of another magnet.
• What are the key features of magnetic fields?


  • Field lines go from the north pole to the south pole.
  • The closer the field lines, the stronger the magnetic field.
  • The magnetic field is strongest at the poles of a magnet.
  • A uniform magnetic field can be created between two opposite poles of a magnet.
• How does Earth's magnetic field behave?


  Earth's magnetic field behaves like a large bar magnet with a magnetic north and south pole.
• What happens when an electric current flows through a wire?


  It generates a magnetic field around the wire.
• What is the shape of the magnetic field around a wire carrying current?


  The magnetic field is circular around the wire.
• How do you use the right-hand rule for current in a wire?


  Point your thumb in the direction of the current, and your fingers will curl in the direction of the magnetic field lines.
• What is a solenoid?


  A solenoid is a coil of wire that produces a magnetic field when an electric current flows through it.
• What is the magnetic field like inside a solenoid?


  The magnetic field inside a solenoid is strong and uniform.
• How can the strength of the magnetic field in a solenoid be increased?


  • Increasing the current.
  • Adding more turns to the coil.
  • Inserting an iron core into the solenoid.
• What is an electromagnet?


  An electromagnet is a type of magnet whose magnetic field is produced by an electric current.
• What are the factors affecting the strength of electromagnets?


  The strength of electromagnets is affected by the current, the number of turns in the coil, and the presence of a soft iron core.
• What are some uses of electromagnets?


  • In motors and generators.
  • In devices like electric bells, relays, and loudspeakers.
  • MRI machines in hospitals.
  • Magnetic cranes in scrap yards.
• What is the motor effect?


  The motor effect is when a current-carrying conductor experiences a force in a magnetic field.
• What does Fleming's Left-Hand Rule help determine?


  It helps determine the direction of the force on a current-carrying conductor in a magnetic field.
• What are the components of Fleming's Left-Hand Rule?


  • Thumb: Direction of the force (motion).
  • First finger: Direction of the magnetic field (north to south).
  • Second finger: Direction of the current (positive to negative).