UNIT 7 SUMMARY

UNIT 7 BLOGPOST SUMMARY

Magnetism

In this past unit we covered A LOT of important information. The subtopics were ... 

• Magnetism (magnetic poles & electromagnetism)
• Forces on charged particles in an electric field (motors)
• Electromagnetic induction and common applications
• Generators and Energy Production
• Transformers and Energy transfer from Power company to Home

Magnetism -->

Magnetism included magnetic poles, electromagnetism, domains, magnetic fields, cosmic rays and compasses. The source of all magnetism is moving charges. 

1. There are magnetic poles at each side of the earth. It is important to remember that the South and North are opposite from what we generally know them as when you draw your diagram. To show the magnetic field lines through the N and S poles, you must draw the magnetic field lines from S to N, out and around the earth and then back down. 
2. Domains show whether or not an object is magnetised. We use many arrows going in the same direction to show that it is strongly magnetised and just a couple of arrows, but all going different directions to show that it is unmagnetized. 
3. A compass is a device that shows the same direction of the magnetic field
4. Newton's 3rd Law tells us that both sides of a permanent magnet have the same force
5. If you had to show the magnetic field lines around a current carrying wire, if the I —> back to front (down) <— I front to back (up)

Forces on charged particles in an electric field (motors) -->

In this section, we focused on Cosmic rays and motors

1. Cosmic rays are charged particles moving through space which cause the phenomena known as the Northern Lights. At the two poles on the earth, the charges are moving parallel to the magnetic field and thus, feeling a force. Therefore, these rays can enter the atmosphere. (Perpendicular would be deflected) 

2. A motor consists of two parts, a current carrying wire and a magnet. A current carrying wire feels a force in a magnetic field. Motors have electrical energy and mechanical energy. In class we made our own motors, and below you can see a short video of mine working!

3. This is also the unit that we learned about the right hand rule where the thumb=force, index= current, middle=magnetic field

Electromagnetic induction and common applications -->

Electromagnetic induction and what it can be applied to was a section that we spent a lot of time on.

1. Electromagnetic induction is the process in which an object feels a force without actually being touched by something else. We learned more about this with traffic lights, metal detectors, and credit card machines. E.G. --> Traffic light... Beneath the concrete, at a traffic stop light, is a loop of wires. When a car moves over the wires, a change in the magnetic field is caused. This, in turn, induces a voltage. The voltage then causes a current and this current sends a signal to the traffic light telling it to change.
2. It is almost the exact same thing in a credit card machine. There is a loop of wires in the machine. When the credit card runs through, it causes a change in magnetic field. The change in magnetic field induces a voltage. The voltage causes a current that carries the message to the machine and signals the machine to tell it who's card it is.

Generators and Energy Production -->

Generators are made of coils of wire and magnets. Generators have mechanical energy and electrical energy. A generator relies on electromagnetic induction (do not get this confused with a motor, a motor relies on a current carrying wire and a force in the magnetic field).

Transformers and Energy transfer from Power company to Home -->

The final topic we focused on was transformers. Transformers are what are seen on the ends of our computer and phone chargers. Here are some facts about transformers...

• Boxes that contain two different loops of wires
• There are step-down and step-up transformers. Step down have more loops of wire on the primary coil and step-up transformers have more loops of wire on the secondary coil.
• Requires AC --> It requires AC because in order to induce a voltage, it needs to have a changing magnetic field. Alternating current is a constant change in current which changes the magnetic field