The strength of the magnetic field between the poles of an electromagnet would be unchanged if :

Options

A. current in the electromagnet winding were doubled
B. direction of current in electromagnet winding were reversed
C. distance between the poles of electromagnet were doubled
D. material of the core of electromagnet were changed

Answer

B

Explanation

Magnetic field strength inside the electromagnet depend on no of turns, Distance between poles, magnitude of current, medium in the core of electromagnet.