MAGNETISM & EMI TEST REVIEWKEY

  1. Describe/draw the following terms:

  1. Magnetic pole- Either of two limited regions in a magnet at which the field of the magnet is most intense, each of which is designated by the approximate geographic direction to which it is attracted.
  2. Magnetic domain - a portion of a ferromagnetic material where the magnetic moments are aligned with one another because of interactions between molecules or atoms.
  3. Magnetic field-a field of force surrounding a permanent magnet or a moving charged particle, in which another permanent magnet or moving charge experiences a force
  4. Permanent magnet-a magnet, often made of alloys of iron, that retains its magnetization after the magnetic field producing it has been removed
  5. Temporary magnet - A magnet, such as that made of soft iron, which retains its magnetism for brief periods.
  6. Electromagnet- a magnet consisting of an iron or steel core wound with a coil of wire, through which a current is passed
  7. Solenoid -A current-carrying coil of wire that acts like a magnet when a current passes through it.

  1. How many poles does every magnet have? 2 What are they?North and South
  2. Describe which poles are attracted to one another and which ones repel.North and South attract, North and North repel, South and South repel.
  3. All magnetism is due to what?Movement of electrons results in a minute magnetic force within the atom. A magnetic field is created as the result of moving charges.
  4. What causes a magnet to have a magnetic field?An electron is really just a cluster of charge, and as the charge moves we see magnetic fields being created at right angles to the movement of charges.
  5. Draw the following magnets and their magnetic fields. Use a star to show where the magnetic field is the strongest.Magnetic field strongest and the poles at the end of the magnets
  6. Bar magnet (north on one side, south on the other)
  7. The north end of one magnet and the south end of another magnet
  8. The north ends of two different magnets
  9. List three ways that a particle will experience a net force of zero in a magnetic field. Particle at rest, motion parallel to magnetic field, or neutral particle. Moving charged particles experience both an electric and magnetic field.
  10. Describe a generator. Be sure to label its parts.

Converts mechanical energy to electricity

A wire loop (armature) rotates in a strong magnetic field to induce a current.

  1. Describe a motor. Be sure to list its parts.

A motor has the same parts as generatorConverts electrical energy into mechanical energy

Current moves through armature inside a magnetic field, making armature turn.

  1. What makes an electromagnet stronger? Weaker?Stronger- increase number of turns or coils of wire OR increase current through wires. Weaker- decrease number of turns or coils of wire , decrease current through wire, OR remove iron core.
  2. Which symbol represents something “coming out” of the page? Which one represents “going in” to the page?
  3. Draw the magnetic field for each of the two sets of wires.

Use RHR #1 (thumb points to arrow which is direction of current)

  1. Attract of repel?
  1. Attract or repel?

  1. How can you cause electric current to flow in a wire, without a battery?Moving the wire through a magnetic field will induce voltage
  2. What causes electrons flow (think back to electricity)? The potential energy difference or voltage.
  3. What is the purpose of any transformer?Converts voltage of AC to higher or lower voltage. Made of two coils of wire wrapped around an iron core.
  4. Describe a step-up transformer.Increases secondary voltage
  5. Describe a step-down transformer.decreases secondary voltage

Make sure you can use RHR #2 to find the poles of an electromagnet!!!