Question

how will you test the magnetic effect of current​

Answer 1

Explanation:

According to SNOW rule, when current flows through a conductor from South to North direction and the wire is held over magnetic needle then the north pole of the magnetic needle deflects towards west. 

Answer 2

Explanation:

1. Put a material in a magnetic field.
2. Run a current through this material.
3. The magnetic field will create a "sideways" change in electric potential across the material - which you can measure.
4. Using this change in potential and the size of the material, you get the magnitude of the magnetic field.