Question

An electric current is created in a long thin wire. How will increasing the current and changing the direction of the current effect the direction that a compass placed under the wire will point?
a. It compass will spin continuously.
b. The compass will flip exactly 180 degrees.
c. The compass will spin exactly 360 degrees.
d. The compass will not react and still point north.

Answer 1

The answer is : B. The compass will spin exactly 360 Degrees

Compass will point out to the earth's magnetic field. If we change the direction of the current , we created an effect which make the compass detect the magnetic field in the exact opposite direction, that is why it will flip exactly 180 degrees

Answer 2

On USATestprep it is B 180 degrease