Electromagnets

Two Reminders 1. A magnet touching a piece of iron can turn the iron into a temporary magnet. 2. Magnets do not need to touch a piece of iron or another magnet to exert a magnetic force on the iron or other magnet because there is a disturbance in the space around a magnet called a magnetic field.

What gives a magnet a magnetic field? In addition to having electric charge, electrons also behave like tiny magnets. In most atoms, the magnetism of electrons near each other line up in opposite directions so that the magnetism of one electron cancels the magnetism of the other. However, this is not the case in certain atoms like iron, nickel and cobalt when they combine to form a solid. N e  S Protons and neutrons also behave like tiny magnets but their magnetism is hundreds of times weaker than the magnetism of electrons.

Magnetic Domains in Iron Within a piece of iron there are very small regions where the magnetism of some electrons in each iron atom line up in the same direction. This makes each tiny region behave like a magnet. Normally, the magnetism in regions next to each other arrange themselves to cancel each other's magnetism.

Magnetic Domains in Iron If a piece of iron is placed in a magnetic field, the magnetism of the electrons in many of the regions will change direction and line up with the outside field. This turns the nail into a temporary magnet. The magnetism of this temporary magnet can be much stronger than the outside magnetic field. S

Electromagnets In 1820, Hans Christian Ørsted discovered that an electric current creates a magnetic field. https://www.planet-schule.de/wissenspool/meilensteine-der-naturwissenschaft-und-technik/inhalt/hintergrund/elektrizitaet/andre-marie-ampere-und-der-elektromagnetismus.html

Electromagnets Because an electric current creates a magnetic field you can build an electromagnet by making an electric current flow around an iron core. Group Challenge: Use this information to build an electromagnet using an iron nail, a wire and a battery.

Engineering Design Challenge Using the available materials, build an electromagnet that can pick up the largest number of paperclips. Research Brainstorm, Select Ideas – Develop a Hypothesis Build Test and Evaluate Iterate – repeat the process

Engineering Design Challenge Claim – statement (or hypothesis) that answers the original question. Usually one sentence in in length. Must be specific. Evidence – scientific data that supports the claim. Can be numbers or observations. Reasoning – explanation that connects the evidence to the claim. Answers why the evidence supports the claim.