An electromagnet's coil has 50 loops. What will happen to the strength of the electromagnet if another 50 loops are added?

An electromagnet's coil has 50 loops. What will happen to the strength of the electromagnet if another 50 loops are added?

• A. Doubles
• B. Increases
• C. Quadruples
• D. Stays the same

Answer: (C)

Magnetic field strength in an electromagnet grows with the total ampere-turns, which is the current times the number of turns. If you keep the current the same and double the number of loops—from 50 to 100—you double the ampere-turns. That direct doubling means the magnetic field in the core becomes stronger by the same factor. So the strength increases, specifically by a factor of two. Quadrupling would require four times as many loops (or four times the current), and staying the same would mean adjusting current to offset the change, which isn’t happening here.

Magnetic field strength in an electromagnet grows with the total ampere-turns, which is the current times the number of turns. If you keep the current the same and double the number of loops—from 50 to 100—you double the ampere-turns. That direct doubling means the magnetic field in the core becomes stronger by the same factor. So the strength increases, specifically by a factor of two. Quadrupling would require four times as many loops (or four times the current), and staying the same would mean adjusting current to offset the change, which isn’t happening here.