Page:Illustrated Astronomy.pdf/51

 • • • AT-HOME EXPERIMENT

How do compasses work?

Doing this short experiment, you will be able to see how a magnetic field interacts with metal particles.

MATERIALS:

· 1 magnet · Steel powder (you can get it from a ball of steel wool) · 1 bowl (plastic or glass) · 1 liter of water

STEP BY STEP

1 · Scrape the steel wool and save the powder you get.

2 · Then, pour down the water in the bowl, and let the steel powder falls.

3 · See that the powder stays mostly on the top of the water (at least the tiny little pieces), and they are randomly spread.

4 · Now, pass the magnet slowly over the water without touching the steel powder.

What differences do you see with what was before the magnet passed?

The minuscule metal particles aligned because the metal dust interacts with the magnetic field that the magnet produces.

That is the basis of how a compass works: a small metal needle is aligned with the Earth’s magnetic field. The compasses stop working when a magnet passes near them since the magnet distorts the magnetic field its needle perceives.

Review questions

1 · Since the Earth was formed, its atmosphere has gone through great changes, what is that for? 2 · Can you mention and describe at least two effects the Moon produces on Earth? 3 · How can we know what is in Earth’s core? 4 · Why Earth does have a magnetic field? 5 · What is the habitable zone or the circumstellar habitable zone? • • • 51