In Class with Dr. Prince: January 2013

Sunday, January 27, 2013

Opposites Attract

Well learning about waves is fun, but like the saying goes: "All good things must come to an end!" I suppose all good things don't need to end because we are going to start a new topic: Magnetism. So for the next week this is all we are going to talk about! What! ONE WEEK! That's right. Here are some magnetism flashcards you can print out or study online.

Standard
Investigate and explain that electric currents and magnets can exert a force on each other. (S8P5c)

Big Idea #1
Magnets can exert a force on an object at a distance.

Big Idea #2
Currents produce magnetism and magnetism can produce currents.

Magnets and Magnetism

Do you remember the definition of a force as described in our energy unit? Did you say a PUSH or PULL? I knew I could count on you to remember. Magnets are composed of two poles and a magnetic field, in which the field lines extend from the North pole towards the South pole. The further away from the magnet, the weaker the force applied to an object. Think about it: How close does a magnet need to be to another magnetic material before it pulls or pushes that object away? Why does a magnet push or pull objects? To answer these questions we will need to look at two magnets. When you place to like poles close to one another, each exerts a force onto the other. They REPEL or push away from one another. On the other hand, when you have two opposite poles close to one another, each one pulls the other closer to it so that they become connected. In this case, they are ATTRACTED to one another.

Does this mean that this can happen with all objects? Well for this we need to see why some materials are magnetic and why others are not. First let's start with magnetic materials.

The magnetic fields of the atoms in magnetic items are aligned. In other words the magnetic field of atoms in the same magnetic domain point in the same direction. Each magnetic domain (group of atoms) can point in different directions, but once they are close enough to a magnet the domains become aligned. The more domains that align result in a stronger magnetization of the material.

The magnetic fields of atoms in nonmagnetic items are weak and and are not aligned. As a result, these materials are unable to show any signs of being magnetized. An example of this would be a piece of chalk. You can move a magnet closer and closer to the chalk and it will never become magnetized.

In a magnet, ALL of the magnetic fields of the atoms are pointing in the same.

In a magnet, ALL of the magnetic fields of the atoms are pointing in the same.

So let's recap:
Nonmagnetic materials have magnetic fields moving in all directions canceling one another out and keeping the material from being magnetized.

Magnetic materials have magnetic fields that point in the same direction within each magnetic domain. These objects can be pulled by magnets.

Magnets have magnetic fields that all point in the same direction from one domain to the next allowing them to be magnetized.

The Earth: A Big Magnet

How cool is this image? The Earth is really just a big magnet! How is the Earth similar to the bar magnet? How is the Earth's magnetic field formed? How does it change over time? How does the magnetic field protect the Earth? Use these two videos to answer these questions.

Video #1

Video #2

Magnets and Health

Some people believe that magnets have healing powers. Why is this so? What do you think according to the research?

The Healing Powers of Magnets
Controlling Chronic Pain with Magnetic Therapy
Can Magnets Cure Pain?

Magnets Producing Currents
Problem Question: Can a Magnet Produce and Electric Current?
Research: Magnets can produce current. [PDF Printable]
You can build a generator at home with these lab instructions to discover the answer.

Currents Producing Magnetism
Problem Question: Can an Electric Current Produce Magnetism?
Research: Current can produce magnetism. [PDF Printable]

Monday, January 21, 2013

Waves Review

Here are a list of questions you can use to prepare for the test this week. Only one copy will be made available to you in school.

Here is everything on the waves unit that we have covered so far. Remember, last week's PowerPoint is available on Edmodo, which you can either access directly from the website or from the mobile apps available for download [Apple] [Google].

Catching the Sound Wave
Colors, Colors Everywhere
Wave Interference and Standing Waves
Do You See What I See?
How Do Waves Behave?
Electromagnetic Waves and Rattlesnakes
Let's Catch the Wave

Good luck this week!

Wednesday, January 16, 2013

A Message from the County

The link for Honors and AP courses for current 8th grade students http://research.zarca.com/k/RQsRVURsRSPsPsPsP is still open and will remain open until February break.

You can apply online only. The link will be placed on our school website and county website. You can apply until February break.

Donna L Broyles
Assistant Principal

Friday, January 4, 2013

Catching the Sound Wave

Before I dive into sound waves perhaps I will share a TV episode on sound waves. Do you remember Ms. Frizzle? Sure you do! She made learning scientific topics quite fun. Check out her students at the sound museum and everything they learn about sound.

How was that? What about those really big vocabulary terms Ms. Frizzle used throughout the show! Now can you answer these questions?

1. How does sound travel?
2. What is the difference between low and high sounds?

I put together some images that we will discuss in class, but only as it relates to more common everyday experiences that you go through.

When sound waves reflect it is called echoing. I am sure you have heard your voice bounce back at you a time or two. What about when your one place and you hear a sound from another place? Perhaps, you can recall a time when you were walking down one hall, but could hear voices in another hall. When sound goes through a narrow opening and spreads out it is called diffraction. When the sound moves around a barrier, it is also called diffraction.

Now, I sure you remember when your parents come to your room and have to tell you to turn your music down. Well why is it that the sound in your room is much louder than the sound outside your room and you haven't even touched the volume? This is where your walls play a role. While the intensity of the sound within the room is high, as the sound travels some of it is absorbed (taken in like water in a sponge) into the walls. This makes the sound on the outside of the room less intense.

Before I tell you more about pitch and frequency, check out this link and see what influences these aspects of a sound. Then when you are done with that link, check out this one as well. When you are done with that link, then check out the simulation below, by clicking the link provided.

http://phet.colorado.edu/en/simulation/sound

Click the link below to begin.

I have put together a quiz for you to try. It will be up each week of this unit. How much do you know about sound waves? Link to test...

I found another website that shares similar information, but I have annotated it so that you can focus on the key areas. Click here!

Have you ever wondered about the why the sound changes from a siren as it passes by? Watch this video!

Music versus Noise: What is the difference between the two? The answer is here!

Surprise, Surprise! Here is a podcast from a small group of students talking through the Properties of Waves lab assignment. Have a listen!

Alright, back to sound waves. I just came across this new application where you can watch 20 second segments of video and answer comprehension questions. Are you up for a challenge? Go ahead and play and let me know your score! Good luck!

Okay, if you have made it to the bottom of this screen then here is something extra special for you. Below is an infographic with a general idea about what we will learn about sound. Remember you will get all the details in class, but you will have at least one more tool in your learning power pack.