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Concept of density. This YouTube video will provide information about the concept of density. It’s great to use as an introduction to the topic or as a way to summarise the topic.

Density of a solid for a regular shaped body. Definition, meaning and its simple calculation

The Earth behaves like a giant bar magnet and as such there is a magnetic field present around it. The Earth’s magnetic field is thought to be caused by flowing liquid metals in the outer core of the planet which causes electric currents and a magnetic field.

The idea of the electric field, how it's useful, and explains how the electric field is defined.

There are many different processes and phenomena that emit electromagnetic radiation. Humans have taken advantage of many of these processes to develop technologies that use electromagnetic radiation.

The beauty of a coral reef, the warm radiance of sunshine, the sting of sunburn, the X-ray revealing a broken bone, even microwave popcorn—all are brought to us by electromagnetic waves. The list of the various types of electromagnetic waves, ranging from radio transmission waves to nuclear gamma-ray (γ-ray) emissions, is interesting in itself.

Even more intriguing is that all of these different phenomena are manifestations of the same thing—electromagnetic waves (see Figure 15.1). What are electromagnetic waves? How are they created, and how do they travel? How can we understand their widely varying properties? What is the relationship between electric and magnetic effects? These and other questions will be explored.

An image that illustrates light reflecting off a plain mirror.

In this lesson you will learn about:

• The concept of magnetism
• Be able to identify magnetic and non-magnetic materials
• Identify properties and types of magnets
• Understand that metals can be magnetised and de-magnetised
• Understand that magnets have a magnetic field
• Understand that the Earth has a magnetic field

Introduction to magnetism: Wikipedia article that provides an overview of the concept.

The force that acts across the air gaps between magnets is the same force that creates wonders such as the Aurora Borealis. In fact, magnetic effects pervade our lives in myriad ways, from electric motors to medical imaging and computer memory. In this chapter, we introduce magnets and learn how they work and how magnetic fields and electric currents interact.