Question

Ms. Rivera is demonstrating an experiment that includes the use of a compass. A compass has a small magnet that rotates to align with Earth's magnetic field. This small magnet of the compass is called a needle. The model below shows the experiment that Ms. Rivera is demonstrating.



What will most likely happen to the compass needle when the switch is closed and the circuit parts are connected to the battery?
A.
It will move because the current in the completed circuit will induce a magnetic field.
B.
It will turn around once because the completed circuit reverses Earth's magnetic field.
C.
It will point toward the batteries because they are the only circuit part that can be magnetic.
D.
It will remain stationary because there are no magnetic materials included in the circuit.

Answer 1

A.

When the switch closes, electric current flows in the circuit and the moving charges create a magnetic field around the wire. The compass needle aligns with the net magnetic field (Earth's field plus the wire's field), so the needle will move (deflect) from its original direction.