Cases for electrically operated instruments are typically made of which material?

Cases for electrically operated instruments are typically made of which material?

• A. Aluminum
• B. Wood
• C. Iron or steel
• D. Plastic

Answer: (C)

Metal enclosures are used because the case must shield sensitive circuitry from electromagnetic interference and provide safe, grounded protection. Iron or steel cases are especially suitable since their high magnetic permeability helps absorb and redirect stray magnetic fields, giving effective shielding of low-frequency interference that can affect instrument readings. They also offer the strength, rigidity, and durability needed to protect delicate components and serve as a solid chassis ground. Wood or plastic don’t provide shielding, and while aluminum can shield some RF, it doesn’t offer the same level of magnetic shielding and mass as steel.

Metal enclosures are used because the case must shield sensitive circuitry from electromagnetic interference and provide safe, grounded protection. Iron or steel cases are especially suitable since their high magnetic permeability helps absorb and redirect stray magnetic fields, giving effective shielding of low-frequency interference that can affect instrument readings. They also offer the strength, rigidity, and durability needed to protect delicate components and serve as a solid chassis ground. Wood or plastic don’t provide shielding, and while aluminum can shield some RF, it doesn’t offer the same level of magnetic shielding and mass as steel.