Question

Why are electromagnets used in metal scrap yards?
A. They are temporary magnets, so they can be turned on or off.
B. They are temporary magnets, so eventually the metal just falls off.
C. They are weak permanent magnets.
D. They are very powerful permanent magnets.

Answer 1

Electromagnets are used in metal scrap yards because they are temporary magnets that can be turned on or off. This feature allows them to easily pick up metal objects and then release them when needed. When an electric current passes through the electromagnet, it creates a magnetic field, attracting metal objects. Once the current is turned off, the magnetic field disappears, causing the metal objects to fall off.

In contrast:

- Weak permanent magnets would not have the same level of magnetic strength needed to efficiently pick up metal objects in a scrap yard.

- Very powerful permanent magnets would not provide the flexibility of being turned on or off as needed, making it difficult to control the picking up and releasing of metal objects.

Therefore, the correct answer is:

A. They are temporary magnets, so they can be turned on or off.

Answer 2

Answer:

The correct answer is A. They are temporary magnets, so they can be turned on or off.

Explanation:

Electromagnets are used in metal scrap yards because they can be easily controlled by adjusting the electric current. When the electromagnet is turned on, it can attract and lift heavy metal objects. When it is turned off, it loses its magnetism, allowing the metal objects to be dropped off at a designated location. This makes electromagnets very efficient and practical for use in scrap yards.