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If a long hollow copper pipe carries a current, then magnetic field is produced

1. outside the pipe only
2. inside the pipe only
3. both inside and outside the pipe
4. no where

Correct answer: outside the pipe only

Solution

According to Ampere's circuital law, the magnetic field inside a hollow conductor carrying current is zero because there is no current enclosed within the hollow region. The magnetic field is produced only outside the pipe.

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