Which involves the use of an electromagnet?
using a compass to find magnetic north
picking up paper clips using a bar magnet
holding up a paper on a metal whiteboard
recording data on a computer hard drive
Picking up paper clips using a bar magnet involves the use of an electromagnet.
The correct answer is: picking up paper clips using a bar magnet.
To determine which option involves the use of an electromagnet, we need to understand the concept of an electromagnet. An electromagnet is a type of magnet that is created by passing an electric current through a coil of wire, which generates a magnetic field. Unlike permanent magnets, electromagnets can be turned on and off by controlling the flow of electricity.
Out of the given options, picking up paper clips using a bar magnet is the one that involves the use of an electromagnet. Although a bar magnet is not an electromagnet itself, it can generate a temporary magnetic field when it is brought near a ferromagnetic material like iron or steel. When the bar magnet attracts the paper clips, it creates a magnetic force that causes them to stick to the magnet. In this case, the bar magnet acts as a makeshift electromagnet by creating a magnetic field that attracts the paper clips.
Using a compass to find magnetic north does not involve an electromagnet because a compass uses a magnetized needle, which aligns itself with the Earth's magnetic field to determine the direction of magnetic north.
Holding up a paper on a metal whiteboard does not involve an electromagnet either. It simply utilizes a magnetic force between the metal whiteboard and the paper, which occurs due to the inherent magnetic properties of the materials used.
Recording data on a computer hard drive also does not involve an electromagnet, despite the fact that hard drives use magnetic storage. In this context, transitions in magnetic orientation are created by a device called a read/write head, which is not an electromagnet but rather a permanent magnet or a magnetized material.
Thus, out of the given options, picking up paper clips using a bar magnet is the only one that involves the use of an electromagnet, as it utilizes the temporary magnetic field generated by the magnet to attract the paper clips.