In Class with Dr. Prince: magnets

Showing posts with label magnets. Show all posts

Sunday, February 3, 2013

Electricity and Circuits

Big Idea #1 - Moving electric charges transfer energy.
Big Idea #2 - Circuits control the flow of electric charge

S8P5c. Investigate and explain that electric currents and magnets can exert force on each other.

From these two images, what can you conclude about magnetic and electric fields?

Static Charge (static electricity) and Static Discharge (static shock, lightning)

Static Charge is the building of electric charges in an object; unbalance number of protons or electrons, thus creating a positive or negative charge.

(click to visit original website)

Questions to Consider:
1. What, from the balloon, is attracting the positively charged particles from the strands of hair?
2. How can a Van de Graaff generator make a person's hair stand on end?

Static Discharge occurs when the build up of charges moves out of an object into a new location.

(click to visit original website)

(Click to visit original website)

Questions to Consider:
1. What is going on in part one of the first image that explains how static discharge works?
2. How can the first image be used to explain the connection between the storm clouds and the ground during the storm in the second image?

Read more...
Moving Electrons and Charges
Electricity and Magnetism Module
Electricity and Magnetism Interactives
Balloons and Static Electricity
Building Circuits Simulation
Ohm's Law Simulation
Electrical Opens and Shorts Simulation
Electromagnets (HS Level)

ELECTRICITY JOKES

Q: How did Ben Franklin feel when he discovered electricity?

A: He was shocked!

Q: Why did the foolish gardener plant a light bulb?

A: He wanted to grow a power plant!

Source: http://mssell.tamu.edu/products/Energy2-web.pdf

S8P5b. Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer energy.

Here are the basic MUST-HAVES for a simple circuit.

The power source is measured in volts (v). The wire path that allows the current to run through is measured in amperes (amp). This lets you know how many electrons pass at a given amount of time. (Sounds like frequency in our waves unit, don't you think?) Then there is the resistor that is measured in ohms (Ω). This measures the amount of resistance in an electrical device, such as a light bulb. Resistors slow the flow of electric charge in a circuit.

What happens when you have an open circuit? What happens when you have a closed circuit?

What does a series circuit look like?

Source: http://www.berkeleypoint.com/images/series.jpg

A series circuit consists of one loop that includes one or more power sources and resistors.

What would the resistors in this model represent? This is a circuit diagram. Each symbol represents one piece of a circuit.

Source: http://www.physics247.com/physics-tutorial/images/seriescircuit.jpg

What does a parallel circuit look like? What do the symbols in the circuit diagram represent?

Source: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi10d2qmaxjlbcV0ZKGEamotXIpI6W8v7Y5HjlgRVKAGEXJrV8lX8IlJ8tqMOphgZYAa0Ql8DPl7waNT8V02yrUjoj_q5IhRk3r1qkwkGlsCWP2qfriTlijaBPVGrXzYpgHv6BPFvg3A8Ak/s1600/Parallel-Circuits.jpg

Ohm's Law

Did you know that there is a relationship between the current, voltage, and resistance from the electrical energy produced in a circuit?

Legend:
The symbol for current is I and the SI unit of measurement is A for amps.
The symbol for voltage is V and the SI unit of measurement is V for volts.

The symbol for resistance is R and the SI unit of measurement is Ω for ohms.

The Relationship:
If you increase the resistance, you decrease the amount of current that can flow through.
If you decrease the resistance, you increase the amount of current that can flow through.

If you increase the voltage, you will increase the amount of current that flows through.
If you decrease the voltage, you will decrease the amount of current that flows through.

Voltage and resistance determine the amount of electrical current flowing through a wire.
If you increase the resistance, then you must increase the voltage.
If you decrease the resistance, then you must decrease the voltage.

How would you draw this one?

Did YOU Know?

Have you ever wondered why some electric plugs have a third prong?

Source: http://www.csionline.org/documents/6thsample.pdf

Read more...
Moving Electrons and Charges
Electricity and Magnetism Module
Electricity and Magnetism Interactives
Balloons and Static Electricity
Building Circuits Simulation
Ohm's Law Simulation
Electrical Opens and Shorts Simulation
Electromagnets (HS Level)

Happy Learning!

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]

Sunday, March 25, 2012

Agenda for March 26 - 30

Parents and Students,
This week we will cover magnetism and electromagnets through various activities, research, and readings. Students will wrapped up this unit with a book on what we cover this week. Students in school on Friday received majority of the research questions. On Monday we will finish the bulk of the research and get started with the activities leading towards the culminating task. Students who are absent the first part of the week will need to come in to help session to get caught up.

There are no journals or pink slips for the remainder of the school year.