Unit D Lesson 11: Electromagnetism and Generators
Completion requirements
Unit D Lesson 11: Electromagnetism and Generators
|
Learning Targets |
Big Question: What is the relationship between electromagnetism and generators?
There is a very close relationship between magnetism and electricity. Motors and generators are examples of how this relationship works for us.
There is a very close relationship between magnetism and electricity. Motors and generators are examples of how this relationship works for us.
At the end of this inquiry, you should be able to answer the following questions:
-
What are the functions of the main parts of a generator?
- What do transformers do?
- What is electromagnetic induction?
Pages 324 and 331 in your textbook will help you answer these questions.
Try It!
Practice Worksheet: Electromagnetic Induction
- DOWNLOAD this practice worksheet (S9_UD_S3_L11_electromagnetic_induction). If you prefer to use a Google Drive or PDF version of the worksheet, click here.
- Answer the questions on the worksheet as you work through the readings and videos in this lesson.
- When you are satisfied with your responses you can check your work by clicking on the "SUGGESTED ANSWERS" button below.
Wait! Don't view the suggested answers first. This practice work is not for marks, it is meant to help you check your understanding. Check the answers AFTER doing the questions! Keep the practice worksheet for study purposes. If you don't understand something, contact your teacher!
-
Hans Christian Oersted discovered that a current carrying wire produces a magnetic field.
-
Michael Faraday discovered that moving a magnet through a wire coil would produce a current.
-
A generator uses mechanical energy (from fossil fuels) to produce electrical energy.
-
I. Iron core
II. Wire
III. Source of energy
-
I. Electromagnets can be used in stereo speakers, motors, and wrecking yards. They are used in schools and hospitals to keep the doors open.
II. Electromagnets are used in devices where mechanical energy is transformed into electrical energy. The most common situation is in electric generators.
Electricity Creates a Magnetic Field
Hans Christina Oersted was a high school teacher who discovered the relationship between a current carrying wire and a magnetic field. Oersted demonstrated that a compass needle would deflect while current went through a wire. This meant that a current produces a magnetic field. This was the first step to discovering the relationship between magnetism and electricity. All motors and generators are based on this relationship today.
Hans Christina Oersted was a high school teacher who discovered the relationship between a current carrying wire and a magnetic field. Oersted demonstrated that a compass needle would deflect while current went through a wire. This meant that a current produces a magnetic field. This was the first step to discovering the relationship between magnetism and electricity. All motors and generators are based on this relationship today.
Watch
Do you want to see how a current creates a magnetic field? to view forms of Oersted's original experiment, watch "Oersted Experiment and
Conceptual Physics: Oersted's Discovery".
A Moving Magnet Produces Electricity
Michael Faraday had a very important discovery regarding magnetism and electricity. Faraday realized from Oersted that electricity produces a magnetic field, so he questioned whether a magnet could produce an electric current. Faraday pushed a magnet through a solenoid coil that was connected to an ammeter. Yes! As the magnet moved in and out of the coil, a current was produced. This was a lasting discovery that gives rise to how we produce electricity through generators around the world.
Watch
Because a current produces a magnetic field, a magnet can induce a current in a wire, as shown in the video "Understanding
Electromagnetic Induction and Electromagnetic Forces".
Electromagnetic Induction
Read “Generating Electricity” on page 329 of your text. Then, try the interactive lab Faraday’s Law Simulation to produce an electrical current by moving a conducting wire through a magnetic field.
Read “Generating Electricity” on page 329 of your text. Then, try the interactive lab Faraday’s Law Simulation to produce an electrical current by moving a conducting wire through a magnetic field.
1. Take the magnet with the cursor and stick it into and out of the coil-move it back and forth a few times. What do you notice happens to the light?
2. What type of energy did you use to produce electrical energy ?
3. Select 2 Coils. Move the magnet through the coil with two wraps at the top. Then move the magnet through the coil with four wraps at the bottom. How does the brightness of the bulb and voltage produced compare?
As you move the magnet in and out of the coil, the bulb lights up.
You use mechanical energy from moving the magnet into and out of the wire to produce electrical energy.
The coil with four wraps produces higher voltage and causes the bulb to glow brighter.
If you would like to see more videos about electromagnetic induction and Farday's Law, watch "Electromagnetic
Induction" and "Electromagnetic Induction and Faraday's Law".
Generators
By looking at Oersted and Faraday's discoveries, you can begin to understand how generators work. Generators use various means of mechanical energy to push large magnets through large solenoid coils of wire to produce current.
In Alberta, fossil fuels are most commonly burned to produce steam which turns turbines. In past years, the fossil fuel was most often coal, but due to climate and pollution concerns, coal-burning is being phased out in favour of cleaning-burning natural gas.
The turbine turns the generator using all the mechanical energy, which the generator converts to electrical energy. Then, the electrical energy is used to power all our devices.
By looking at Oersted and Faraday's discoveries, you can begin to understand how generators work. Generators use various means of mechanical energy to push large magnets through large solenoid coils of wire to produce current.
In Alberta, fossil fuels are most commonly burned to produce steam which turns turbines. In past years, the fossil fuel was most often coal, but due to climate and pollution concerns, coal-burning is being phased out in favour of cleaning-burning natural gas.
The turbine turns the generator using all the mechanical energy, which the generator converts to electrical energy. Then, the electrical energy is used to power all our devices.
Figure 1 – The mechanical energy that turns these large generators is provided by rushing water in a hydroelectric dam.
Watch
Generators use mechanical energy in various forms to make electrical power. Various ways electricity can be generated
are shown in the video "Energy 101: Electricity Generation".
The Electromagnet
Another important experimental discovery was the electromagnet that uses an iron core, some wire, and an electrical source. When current is run through the wire, the iron core turns temporarily into a magnet. Electromagnets serve an important role in motors, and you will learn more about this later in the section.
An interesting use for electromagnets is in scrap metal yards. The crane holds a large iron core that is wrapped in wire. When an electric current goes through the wire around the core, it becomes a temporary magnet.
The giant electromagnet can pick up a car or scrap metal and move it to a new location. By turning off the current, the electromagnet demagnetizes and the load of scrap iron drops. This can also be useful in separating magnetic from non-magnetic scrap materials.
Another important experimental discovery was the electromagnet that uses an iron core, some wire, and an electrical source. When current is run through the wire, the iron core turns temporarily into a magnet. Electromagnets serve an important role in motors, and you will learn more about this later in the section.
An interesting use for electromagnets is in scrap metal yards. The crane holds a large iron core that is wrapped in wire. When an electric current goes through the wire around the core, it becomes a temporary magnet.
The giant electromagnet can pick up a car or scrap metal and move it to a new location. By turning off the current, the electromagnet demagnetizes and the load of scrap iron drops. This can also be useful in separating magnetic from non-magnetic scrap materials.
Figure 2 – A junkyard electromagnet is very powerful, and can move large amounts of magnetic metals.
Watch
Once you understand that an electromagnet is created due the magnetic field that forms around a current-carrying wire, you can start to get creative with electromagnetic applications. In the following video, a very simple "train" is formed when strong
mini-magnets are attached to the end of a dry cell. Because the mini-magnets are metal, electricity from the dry cell is conducting to the surrounding copper coil of wire. With current flowing through it, that portion of the copper coil forms a magnetic
field, essentially becoming a magnet. The magnetism of the min-magnets is attracted to the magnetic field of the coil, causing the mini-magnets (and the dry cell to move). Can you think of applications for this technology?
Generators: Making Electricity From Hot Water in the Ground
There is a great deal of heat energy stored in the Earth. This heat energy can be harnessed to turn turbines to help generate electricity. This form of energy is known as geothermal energy, and it is becoming more and more popular around the world as an environmentally friendly method of generating electricity. Traditionally geothermal has been limited to places in the world where the Earth's crust is thinner, such as in Iceland. Recent advances however, are making geothermal practical in any part of the world.
There is a great deal of heat energy stored in the Earth. This heat energy can be harnessed to turn turbines to help generate electricity. This form of energy is known as geothermal energy, and it is becoming more and more popular around the world as an environmentally friendly method of generating electricity. Traditionally geothermal has been limited to places in the world where the Earth's crust is thinner, such as in Iceland. Recent advances however, are making geothermal practical in any part of the world.
Figure 3 – Geysers are a good sign that an area is geologically active, and there is plenty of heat just below the Earth's surface. This geyser is in Iceland, a country that uses geothermal energy to provide most of their electricity.
Watch
To see how the power of Geysers is turned into electricity, watch "Geothermal Power: How does it work?"