cp10-11

• Name three magnetic materials.

  Iron, nickel, cobalt
• What is a magnetic field?

  The space around a magnet affecting materials
• What is an induced magnet?

  A magnetic material that becomes a magnet
• How can we find the shape of a magnetic field?

  • Using a compass
  • Using iron filings
• Describe the right-hand grip rule.

  Thumb points current direction, fingers curl magnetic field
• What is a solenoid?

  An electromagnet made with a wire coil
• How do you draw the magnetic field around a solenoid?

  • Draw concentric circles around the solenoid
  • Indicate direction with arrows
• What is the motor effect?

  A force on a wire in a magnetic field
• What does Fleming's Left Hand Rule illustrate?

  • Direction of force
  • Current direction
  • Magnetic field direction
• What happens to the force on a wire if we change the direction of the current?

  The force changes direction
• What is the equation for force on a conductor in a magnetic field?

  Force = magnetic flux density x current x length
• What do transformers do?

  Change the potential difference of electricity
• How is a transformer made?

  Using two coils of wire on an iron core
• What does the law of conservation of energy mean in a transformer?

  Power in primary equals power in secondary
• What is the equation to demonstrate conservation of energy in transformers?

  Pd across primary x current in primary = pd across secondary x current in secondary
• Why do we increase the pd across the national grid?

  To decrease current and reduce heat loss
• What type of transformer decreases the pd before it goes to homes?

  Step-down transformer
• How can we increase the pd induced in a wire?

  Increase turns in wire or magnetic field movement
• How do transformers work?

  AC creates changing magnetic field inducing pd
• What does a current flowing through a wire create?

  A magnetic field
• How can the magnetic field around a wire be demonstrated?

  Using iron filings or a plotting compass
• What does the right hand grip rule indicate?

  Magnetic field direction relative to current
• What is a permanent magnet?

  A bar magnet that is always magnetic
• What materials can a magnet attract?

  Iron, steel, nickel, and cobalt
• What is the magnetic field?

  The space around a magnet that attracts materials
• What are the two poles of a bar magnet?

  North (N) and South (S)
• What happens when like poles of magnets are brought together?

  They repel each other
• What occurs when a magnetic material is placed in a magnetic field?

  It becomes an induced magnet
• How can the shape of a magnetic field be visualized?

  Using plotting compasses
• Where is the magnetic field strongest?

  Where the field lines are closest together
• How does the Earth's magnetic field compare to a bar magnet?

  It is similar in shape
• What affects the strength of a magnetic field created by a current?

  The size of the current
• What happens when a wire is made into a coil?

  It becomes a solenoid with a stronger field
• How do the fields from individual coils in a solenoid behave?

  They add together inside, cancel outside
• What can any wire carrying a current experience?

  A force near a magnetic field
• When does the greatest force occur on a wire in a magnetic field?

  When the wire is at right angles
• What does Fleming’s Left Hand Rule illustrate?

  The relationship between force, field, and current
• What is an electromagnet?

  A coil of wire with current flowing through it
• How can the magnetic field of an electromagnet be strengthened?

  By adding an iron core
• What happens to the iron core in an electromagnet?

  It becomes a temporary magnet