Natural Science, Unit 8: Electricity and Magnetism This slideshow will tell you everything you need to know from Unit 8 of Natural Science… Pay attention!

Insulators Insulators are materials that do not pass energy through them easily. Examples include: glass, plastic, porcelain, rubber and wood. We use insulators to protect ourselves from electricity. Insulators can also be called non-conductors.

Conductors Conductors are dense materials that pass energy between particles easily. Examples include: copper, water and silver.

Benjamin Franklin He created the lightning rod, which is important for modern society as it helps to protect us from being struck (hit) by lightning! He used a kite and a Leyden jar (which stored electrical energy like a battery) to learn about electricity.

HANS CHRISTIAN ØRSTED (1777-1851) Hans Christian Orsted discovered the relationship between electricity and magnetism. The unit for measuring magnetism- Oersted- is named after him. His discoveries led to the development of electromagnets.

Electricity Electricity is the movement of electrons. Electricity begins in atoms. Atoms are made of protons and neutrons inside a nucleus. Electrons move around outside the nucleus. Protons have a positive electrical charge. Neutrons have no electrical charge. Electrons have a negative electrical charge. Electrons can sometimes move easily from one object to another, which results in objects becoming electrically charged. Electricity is the movement of electrons.

Electrical charges Electrical charges repel or attract each other, the same as magnets. Negative charges are attracted to positive ones. Negative repels negative and positive repels positive.

Static electricity Static means ‘still’ or ‘not moving’. Static electricity is a form of electricity that doesn’t flow. If static electricity forms a negative charge, it will be stored in particles until a positively charged object is nearby. Then, it will ‘jump’ from negative to positive. The electric shock feeling that you get from a supermarket trolley or a slide is made possible by static electricity.

Current Electricity When electrons move from one object to another, this creates electrical current. We can trap this in a circuit using conductors like copper or silver wires .

Electrical Circuits Closed electrical circuits pass the flow of electrons around in a circle. An electrical circuit has the following parts: A power source provides energy Wires conduct electricity A switch opens and closes the circuit A resistor changes the electricity into different types of energy

Magnetism Types of magnets Magnets have poles (ends), the same as planet Earth- North and South. If you put two North poles together, they will push each other apart (repel). If you put two South poles together, they will repel. If you put North and South together, they will move towards each other. This is called magnetic attraction. Can be natural (like certain minerals) or man-made, like electro-magnets. Minerals such as magnetite, iron, nickel and cobalt are magnetic. Types of magnets Permanent magnets never lose their magnetism Induced or temporary magnets lose their magnetism over time

Magnetic Field The liquid iron core of Earth makes it act like a huge magnet. It creates a magnetic field, like all magnets, that protects us from cosmic rays and protects our atmosphere. Some parts of cosmic rays can enter the atmosphere at the magnetic North and South poles. We can see them as lights- the Aurora Borealis (North) and the Aurora Australis (South). The more magnetic something is, the bigger its magnetic field will be. The area around a magnet that attracts magnetic objects is called a magnetic field. We can see a magnetic field by putting a magnet in an area of magnetic iron filings.

What things are magnetic? Iron and steel (but not stainless steel) are magnetic. We can make magnets from other, non-magnetic metals that are good conductors. Electromagnets are magnets created by passing electricity through certain types of metal objects to create a magnetic field. Magnetic materials are always metallic, but not all metals are magnetic.

Electromagnets

What do we use electromagnets for? Electromagnets are used in security, trains, speakers, disks, microphones, hairdryers, TVs, keycards, bank cards and MRI scanners. These are just a few examples!