Electromagnets exercise

A wire was spotted protruding from a wall. Both Jonathon and Stephen wanted to know if a current was flowing through the wire. They placed two magnetic compasses near the wire as shown in the animation on the right.

Jonathon concluded that the wire carried a steady current. Stephen thought that someone was turning the switch off and on and did not agree with Jonathon.

Who is right? Explain.

Irene bought a new house and found that an unknown wire was coming up through a hole in the floor. She wanted to know if it had a current running through it. She placed two magnetic compasses around the wire and noticed the deflection of the needles.

Is there a current flowing through the wire? How can you tell?
If a current is flowing how is it changing? Explain.

An electrician was working on a building site when he came upon an insulated wire. He was told that all the power to the site was turned off, but he wanted to make sure. He pulled out a magnetic compass and placed it near the wire as shown in the animation on the right. What can he conclude from his observations?
A magnetic compass was brought close to two wires as shown on the left. What can you conclude from your observations?
The elastic band provides the tension to automatically close the gate. Metal contacts that complete the circuit and cause the light to glow when the gate is shut The light indicating if the gate is open or closed An electromagnet that activates the lock The bolt that is lifted through a scre eye by the electromagnet The gate
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