Unit D Lesson 6: Controlling Electricity
Completion requirements
Unit D Lesson 6: Controlling Electricity
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Learning Targets |
Big Question: How can we control electricity?
Almost all of our useful electricity flows through circuits. Circuits are combinations of wires, switches, and other useful parts that harness the usefulness of electricity.
Almost all of our useful electricity flows through circuits. Circuits are combinations of wires, switches, and other useful parts that harness the usefulness of electricity.
At the end of this inquiry, you should be able to answer the following questions:
- What is the difference between conductors and insulators?
- What is the difference between a resistor and a variable resistor?
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What is meant by resistance?
Pages 296 to 302 in your textbook will help you answer these questions about how to control electricity.
Introduction
Conductors and Semi-Conductors
Conductors are materials that allow electric current to flow through them easily. This is opposite to insulators , which hold electrons tightly and, therefore, do not allow current to flow through them as easily. Section 1.3 explained how effective insulators are used for safety. For example, wires used to conduct electricity are covered with effective insulating material to protect us from electrical shock.
Semi-conductors can have properties of a good conductor or a good insulator depending on the environment they are in.
Conductors are materials that allow electric current to flow through them easily. This is opposite to insulators , which hold electrons tightly and, therefore, do not allow current to flow through them as easily. Section 1.3 explained how effective insulators are used for safety. For example, wires used to conduct electricity are covered with effective insulating material to protect us from electrical shock.
Semi-conductors can have properties of a good conductor or a good insulator depending on the environment they are in.
- What materials make good conductors?
- What materials make good insulators?
Watch
Watch the video "Physics - Conductors and Insulators".
Watch the video "Conductors, Insulators and Semi-conductors".
Watch the video "Conductors and Insulators".
Try It!
Practice Worksheet: Conductors and Insulators
- DOWNLOAD this practice worksheet (S9_UD_S2_L6_conduct_insulate). If you prefer to use a Google Drive or PDF version of the worksheet, click here.
- Click here
to visit the simulation website. To complete this simulation, drag each object down to hook it up to the lightbulb with the alligator clips. Once you have tested an item, move it back up to the top of the page. Complete the worksheet.
*Please note that you need Adobe Flash activated on your computer for this simulation to work. If you cannot get this simulation to work, don't worry, this activity and worksheet is optional. Just make sure to read pages 298-302 in the
Science in Action textbook carefully.
- 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!
1. Salt solutions, metals, and graphite are better at conducting electricity.
2. Wood, plastic, glass, and water are better at insulating electricity.
Interactive
Electrical Conductors and Insulators
- What makes a good conductor? What makes a good insulator? Visit this DK page: "Conductors and Insulators" to review what you learned in this lesson. Read the whole page, and be sure to click on the terms in the diagrams.
- In the bottom left corner of the Conductors and Insulators page, you will see "Take our electricity quiz!" – be sure to give the quiz a try!
Resistance and Resistors
A conductor has little resistance and allows electrons to flow through it easily, but an insulator provides much resistance and does not allow electrons to travel through it easily. Resistance is measured by looking at how much current (electrons) flow through the material. Less resistance means an increase in current; more resistance means a decrease in current. Resistance is measured in ohms with the symbol Ω.
A conductor has little resistance and allows electrons to flow through it easily, but an insulator provides much resistance and does not allow electrons to travel through it easily. Resistance is measured by looking at how much current (electrons) flow through the material. Less resistance means an increase in current; more resistance means a decrease in current. Resistance is measured in ohms with the symbol Ω.
Figure 1 – In circuit diagrams, resistors are show as a row of triangular waves in the wire.
Watch
For an alternate explanation on resistance, you can watch "Resistance in Circuits".
For another explanation watch "Resistance".
Watch "Resistance in a Wire".
Resistors
A type of conductor used in many devices is called a resistor. It allows electric current to go through it, but it provides some resistance to how fast the current can flow.
A practical application of resistors is in our everyday devices such as an incandescent light bulb that uses tungsten, a good resistor, to slow the flow of electrons in the glass bulb. The energy from the buildup of electrons turns into light and heat. A resistor can be variable, which means we can change the resistance. This type of resistor is called a rheostat or a variable resistor. Dimmer switches and volume controls work by using rheostats.
A type of conductor used in many devices is called a resistor. It allows electric current to go through it, but it provides some resistance to how fast the current can flow.
A practical application of resistors is in our everyday devices such as an incandescent light bulb that uses tungsten, a good resistor, to slow the flow of electrons in the glass bulb. The energy from the buildup of electrons turns into light and heat. A resistor can be variable, which means we can change the resistance. This type of resistor is called a rheostat or a variable resistor. Dimmer switches and volume controls work by using rheostats.
Watch
How is a sewing machine pedal a resistor? Watch the video "Sewing Machine Rheostat" to see a rheostat and how it can change the current flow.
Rheostats
Rheostats control the levels of resistance in currents. A practical application of this is the volume variability in a stereo.
Similar to rheostats, switches can control electricity, also. However, switches are either closed to turn on or open to switch off the current. The switch is a control, and is one of the four basic components to all circuits as you saw in Lesson D2.
Rheostats control the levels of resistance in currents. A practical application of this is the volume variability in a stereo.
Similar to rheostats, switches can control electricity, also. However, switches are either closed to turn on or open to switch off the current. The switch is a control, and is one of the four basic components to all circuits as you saw in Lesson D2.
Watch
Watch the video "The Rheostat" to learn how to make a simple rheostat.
Superconductors
Wouldn't it be cool to ride all over the country on a floating train? This is already being tested in some countries using superconductors. These trains are called 'maglev' (magnetic levitation) because of the strong magnetic field the trains float on. The strong magnetic field is created when electricity flows through the superconductive materials under the train.
Superconductors are the 'ultimate' conductor offering little to no resistance. Scientists have been able to super-cool materials to allow them to become a superconductor and have magnetic properties.
Wouldn't it be cool to ride all over the country on a floating train? This is already being tested in some countries using superconductors. These trains are called 'maglev' (magnetic levitation) because of the strong magnetic field the trains float on. The strong magnetic field is created when electricity flows through the superconductive materials under the train.
Superconductors are the 'ultimate' conductor offering little to no resistance. Scientists have been able to super-cool materials to allow them to become a superconductor and have magnetic properties.
Watch
Superconductors sound amazing. Imagine if you could hold one in your hands; watch as "Boaz Almog "levitates" a superconductor".
If you are interesting in learning more about the "Physics of Maglev trains", watch this video.