The work done on or by a unit N-pole in moving once around a closed path is equal to

• A. Magnetic flux density
• B. The product of current and number of turns enclosed by that path
• C. The product of flux and number of turns enclosed by that path
• D. Reluctance

Answer: (B)

Ampere works law or Circuital Law
This law relates to work done in a magnetic circuit i.e. closed magnetic flux path.
The work done on or by a unit N-pole in moving once round any complete path is equal to the product of current and number of turns enclosed by that path