The Repulsion Test: To determine if an unknown object is a permanent magnet, it must be tested against a known magnet. If the object is repelled by the known magnet, it is a permanent magnet. If it is only attracted, it is merely a magnetic material.
Creating Induced Magnets: Magnetism can be induced by placing a material in a strong magnetic field or by 'stroking' a magnetic material with one pole of a permanent magnet in a consistent direction to align its internal structure.
Field Mapping: The presence of a magnetic field (permanent or induced) can be visualized using plotting compasses or iron filings. Field lines always exit from the North pole and enter the South pole.
Identify the Material First: Always check if the substance mentioned is magnetic (Iron, Steel, Nickel, Cobalt). If the question mentions Copper or Aluminum, there will be no magnetic interaction regardless of the magnet's strength.
The 'Only' Rule: Remember that repulsion is the only definitive proof of a permanent magnet. Attraction is ambiguous because it occurs between two opposite poles OR between a magnet and an unmagnetized magnetic material.
Field Direction: When drawing or identifying fields, ensure arrows point from North to South. In induced magnetism diagrams, label the poles of the material based on the 'opposite attracts' rule relative to the permanent magnet.
The 'All Metals' Myth: A frequent error is assuming all metals are magnetic. Students often incorrectly identify Aluminum or Brass as magnetic materials because they are metallic.
Induced Repulsion: Students often mistakenly think an induced magnet can repel a permanent magnet. Because induction is caused by the field itself, it naturally aligns the material into an attractive configuration.
Steel vs. Iron: While both are magnetic, steel (hard) is used for permanent magnets because it retains magnetism, whereas iron (soft) is used for temporary applications like electromagnets.
