ELECTRICITY

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ELECTRICITY MAGNETISM

• BY Arana Rampersad
• Form 5D
• Physics

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MAGNETISM

• PERMANENT MAGNETS

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MAGNETISM

• Magnetism is a force that acts at a distance
  and makes a magnet
• Attract and repel other magnets
• Attract iron, nickel, cobalt and a few other
  substances.

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Simple activity to identify the poles of a
magnetic dipole

• A dipole is a pair of electrical charges or
  magnetic poles of equal magnitude but opposite
  polarity, separated by some (usually small)
  distance. The direction of the dipole moment
  corresponds to the direction from the negative to
  the positive charge or from the south to the
  north pole.
• Permanent magnets mean that the material
  maintains a magnetic field with no external help.
  The characteristic of any magnetic material to do
  so is called retentivity.

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Simple activity to identify the poles of a
magnetic dipole

• ACTIVITY
• SUSPENDING A MAGNET
• Have a magnet freely suspended so that it can
  swing in a horizontal plane.
• Wait until it comes to a rest in an approximate
  north- south direction after oscillating to and
  fro for a short time.
• The magnet may be regarded as having a magnetic
  axis and it would come to rest with this axis in
  a vertical plane called the magnetic meridian.
• The pole which points towards the north is called
  the north seeking or simply N pole the other is
  called the south seeking or S pole.

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MAGNETISM

• MAGNETIC FORCES

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Simple experiment which show that a repulsive
force exists between like poles and attractive
force between unlike poles

• EXPERIMENT Action of One Magnet on Another.
• Suspend a fairly strong magnet.
• Put the N pole of the magnet near the N pole of
  another magnet repulsion would occur. (Repulsion
  would also occur with two S poles).
• Put the N pole of the magnet near the S pole of
  another magnet attraction would occur.
• It can be concluded that like poles repel and
  unlike poles attract.

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Simple experiment which show that a repulsive
force exists between like poles and attractive
force between unlike poles

• Unlike magnetic
  poles attract.
• Like magnetic poles repel.

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Effects of the separation of magnets on the
magnitude of the force between them

• When a strong magnet is placed on a balance
  (north pole facing up) and the reading is
  recorded, a second magnet is placed directly
  above the magnet (north pole facing down).
• The balance reading would increase due to the
  repulsive forces between the magnets.
• If the distance between the magnets gets closer,
  the repulsive force would increase.

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Effects of the separation of magnets on the
magnitude of the force between them

• The force of attraction between magnets depends
• Directly on the strengths of the magnets
• Inversely on the square of their distance apart.
• The closer the two magnets are the greater the
  force between them.

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Differentiate between magnetic and non magnetic
materials

• Magnetic Materials
• Materials such as iron, cobalt and nickel.
• Attracted to magnets.
• The domains of the magnetic fields align
  themselves in an orderly fashion.
• Consists of tiny magnets called domains which has
  its own north and south pole.
• Has strong magnetic alloys that are described as
  ferromagnetic.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

• Non Magnetic Materials
• Materials such as copper, glass, brass and wood.
• Not attracted to magnets.
• The domains of the magnetic fields are randomly
  aligned and tends to cancel out.

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How a magnet can attract an unmagnetized object

• A magnet can attract an unmagnetized object by
  the process of magnetic induction. This is where
  an unmagnetized material for example steel is
  place near to or in contact with a pole of a
  magnet. When it is removed the object would be
  magnetized. This is because the magnetic field of
  the magnet is causes the internal molecular
  magnets or domains of the steel to align
  themselves in the same direction.