Shielding in analog meters primarily protects against stray magnetic fields.

Shielding in analog meters primarily protects against stray magnetic fields.

• A. Damage due to careless handling.
• B. Harmful UV rays.
• C. Over-current and surges.
• D. Stray magnetic fields.

Answer: (D)

Shielding in analog meters is about reducing interference from external magnetic fields. Analog meters use a delicate magnetic movement (like a moving coil) to indicate the measurement, so stray magnetic fields nearby can exert unwanted torque on the coil and distort or drift the reading. Placing shielding material around the meter—often high-permeability metals—helps redirect or absorb those external fields, so the coil responds primarily to the intended measurement field. That’s why shielding is primarily about stray magnetic fields. The other options don’t fit this purpose: damage from careless handling is a physical protection issue, not magnetic shielding; harmful UV rays don’t affect the magnetic mechanism of analog meters; over-current and surges are electrical protection concerns handled by fuses and surge devices rather than shielding.

Shielding in analog meters is about reducing interference from external magnetic fields. Analog meters use a delicate magnetic movement (like a moving coil) to indicate the measurement, so stray magnetic fields nearby can exert unwanted torque on the coil and distort or drift the reading. Placing shielding material around the meter—often high-permeability metals—helps redirect or absorb those external fields, so the coil responds primarily to the intended measurement field. That’s why shielding is primarily about stray magnetic fields.

The other options don’t fit this purpose: damage from careless handling is a physical protection issue, not magnetic shielding; harmful UV rays don’t affect the magnetic mechanism of analog meters; over-current and surges are electrical protection concerns handled by fuses and surge devices rather than shielding.