Why is the protective outer casing of a magnetic compass always made of materials like brass, aluminum, or…

Why is the protective outer casing of a magnetic compass always made of materials like brass, aluminum, or plastic, but never iron or steel?
  1. Iron causes the compass to become too heavy for travel
  2. An iron casing would attract the magnetic needle inside and interfere with accurate directional readings
  3. Brass and plastic conduct Earth's magnetic field much faster than iron
  4. Iron reacts with air to make the compass glass opaque

Solution

Magnetic materials like iron would become magnetized or attract the compass needle, preventing it from pivoting freely toward Earth's magnetic poles.

Asked in: Homi Bhabha Practice

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