The strength of a magnetic field around a wire carrying a current of 20 cap A is 0 point 0 0 4 cap t What is the strength of the magnetic field if the current is changed to 40 cap A ?

For the same wire and measurement distance, magnetic field strength is directly proportional to current. The current doubles from 20 A to 40 A, so the field doubles from 0.004 T to 0.008 T. Therefore, the correct choice is 0.008 T.

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