In this unit you will learn...
- To understand the conditions necessary to light a bulb by connecting it to a battery with wires
- To compare bulb brightness according to the manner in which a bulb is connected to a circuit
- To learn how to safely and efficiently use electricity and put that learning into practice.
Useful Informative Websites
Lesson 1: What is Static Electricity?
How to Make Your Hair Stand on End.
You can try this experiment at home.
Equipment Needed
What is a Prediction?
When you are asked to make a prediction; you should say what you think is going to happen.
What is a hypothesis?
A hypothesis is an educated guess, or a guess you make based on information you already know.
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Method
Step 1 – Begin the experiment by blowing up the balloon. Then take a moment to make some observations. Is there anything special about the balloon? What if we move the balloon toward your hair, do you think anything will happen? Write down your hypothesis (prediction) and then test to see if you were right! Step 2 – Wave the balloon about 2-3 inches above your head. Does anything happen? No, the hair stays in place. Was your hypothesis correct?
Step 3 – Rub the balloon back and forth on a sweater or t-shirt for 5 to 10 seconds. Then make some more observations. Does it look like there is anything different about the balloon? Do you think anything different will happen if we move the balloon toward your hair? Write down your hypothesis (prediction) and then test to see if you were right!
Step 4 – Wave the balloon about 2-3 inches above your head again. Does anything happen this time? Was your hypothesis correct? Wondering what caused your hair to move? Find out the answer in the section below.
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How Does this Science Experiment Work?
Most objects do not have a positive or negative charge, they are neutral. Some objects, like balloons, have the ability to become charged. At the beginning of the experiment, when you wave the balloon over the person’s hair and place the balloon against a wall, the uncharged (neutral) balloon does not attract the person’s hair or stick to the wall. By rubbing the balloon on your shirt, you are giving it an electrical charge. Rubbing the balloon allows electrons from your shirt to move onto the balloon. This gaining of electrons gives the balloon an overall negative charge. When you wave the balloon over the person’s hair now, it stands on end. This is because the negative charges of the balloon attract the positive charges of the person’s hair. When you place the balloon against a wall, the balloon sticks to the wall. This is because the negative charges of the balloon attract the positive charges in the wall. Unlike electric charges attract each other. The outcome of this experiment is a result of static electricity.
Static electricity is a stationary (not moving) electric charge that is caused by friction.
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Now watch the video below to learn more about static electricity.
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Lesson 2: What is Static Electricity?
How to Make a Balloon Stick to a Wall.
You can try this experiment at home.
Equipment Needed
• Balloon • An object made out of wool (such as a sweater, scarf, blanket or ball of yarn) • Stopwatch • A wall • A partner (optional) Preparation
What is a hypothesis ?A hypothesis is an educated guess, or a guess you make based on information you already know. After you make a hypothesis, then comes the really fun part: doing the science experiment to see what happens.
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Method
Review:
Was your hypothesis correct? Extra ActivitiesA: Does rubbing in one direction give a different result than rubbing back and forth? Try comparing the same number of rubs in one direction with those done back and forth. Does one stay on the wall longer than the other?
B: Try comparing the effectiveness of different materials for producing a static charge. Does rubbing wool work better than rubbing silk? Design an experiment to test several different materials: silk, wool, nylon, polyester, plastic, metal, etcetera. |
How Does this Science Experiment Work?
In general, the balloon should stick to the wall for a longer amount of time as you increased the number of times you rubbed the balloon on the woolly object. This is because wool is a conductive material, which means it readily gives away its electrons. Consequently, when you rub a balloon on wool, this causes the electrons to move from the wool to the balloon's surface. The rubbed part of the balloon now has a negative charge. The more you rubbed your balloon against the wool the more electrons your balloon should have collected thus increasing the balloons negative charge. Objects made of rubber, such as the balloon, are electrical insulators, meaning that they resist electric charges flowing through them. This is why only part of the balloon may have a negative charge (where the wool rubbed it) and the rest may remain neutral.
When the balloon has been rubbed enough times to gain a sufficient negative charge, it will be attracted to the wall. Although the wall should normally have a neutral charge, the charges within it can rearrange so that a positively charged area attracts the negatively charged balloon. Because the wall is also an electrical insulator, the charge is not immediately discharged. However, because metal is an electrical conductor, when you rub the balloon against metal the extra electrons in the balloon quickly leave the balloon and move into the metal so the balloon is no longer attracted and does not adhere.
When the balloon has been rubbed enough times to gain a sufficient negative charge, it will be attracted to the wall. Although the wall should normally have a neutral charge, the charges within it can rearrange so that a positively charged area attracts the negatively charged balloon. Because the wall is also an electrical insulator, the charge is not immediately discharged. However, because metal is an electrical conductor, when you rub the balloon against metal the extra electrons in the balloon quickly leave the balloon and move into the metal so the balloon is no longer attracted and does not adhere.
A conductive material is any material that allows electricity to flow through it.
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Now watch the video below to learn more about static electricity.
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Lesson 3: What can Static Electricity do?
How to Move Things Without Touching Them.
Introduction
Everything in the world consists of tiny particles called "atoms." Atoms contain even tinier particles called "protons," "neutrons" and "electrons." Most atoms are neutral, which means the protons (positive-charge particles) are balanced with the electrons (negative-charge particles), so they cancel each other out. Sometimes, however, the outer layer of an atom gets rubbed off. This creates atoms with a slightly positive charge. The item that rubs off the outer layer of the atom “steals" some of the extra electrons, giving it a slightly negative charge. We call this built-up electric charge "static electricity."
When you come in from playing in the snow and remove your hat, the hat rubs your hair and electrons move from your hair to the hat, creating a static charge. When objects have the same charge, they repel each other, which means they try to get as far from each other as possible. This is why static electricity makes your hair stand up. Each hair has a positive charge and repels against the other hairs.
When people think of static electricity, they often think of the shock it can cause. If you have ever scooted your sock-covered feet across the carpet, you have probably experienced the zap of static electricity. As you walk over carpet in socks, your feet rub electrons off the carpet, leaving you with a slightly negative static charge. When you reach for a doorknob, you get a shock as electrons jump from you to the knob, which conducts electricity.
You've probably noticed that static electricity is more noticeable during the winter months. This is because the air is very dry. In the summer, the humidity and moisture in the air help electrons move more quickly, which makes it harder to build up a big static charge.
In this lesson we are going to see how static electricity can also be used to move objects without us touching the object.
Everything in the world consists of tiny particles called "atoms." Atoms contain even tinier particles called "protons," "neutrons" and "electrons." Most atoms are neutral, which means the protons (positive-charge particles) are balanced with the electrons (negative-charge particles), so they cancel each other out. Sometimes, however, the outer layer of an atom gets rubbed off. This creates atoms with a slightly positive charge. The item that rubs off the outer layer of the atom “steals" some of the extra electrons, giving it a slightly negative charge. We call this built-up electric charge "static electricity."
When you come in from playing in the snow and remove your hat, the hat rubs your hair and electrons move from your hair to the hat, creating a static charge. When objects have the same charge, they repel each other, which means they try to get as far from each other as possible. This is why static electricity makes your hair stand up. Each hair has a positive charge and repels against the other hairs.
When people think of static electricity, they often think of the shock it can cause. If you have ever scooted your sock-covered feet across the carpet, you have probably experienced the zap of static electricity. As you walk over carpet in socks, your feet rub electrons off the carpet, leaving you with a slightly negative static charge. When you reach for a doorknob, you get a shock as electrons jump from you to the knob, which conducts electricity.
You've probably noticed that static electricity is more noticeable during the winter months. This is because the air is very dry. In the summer, the humidity and moisture in the air help electrons move more quickly, which makes it harder to build up a big static charge.
In this lesson we are going to see how static electricity can also be used to move objects without us touching the object.
You can try this experiment at home.
Equipment Needed
Preparation
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Method
How Does this Science Experiment Work?The can rolls because, basically, you pile up electrons on one thing and use them to attract the protons in something else. When you rub a balloon on your hair, it ends up loaded with electrons. Those electrons can attract the protons in a can.
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Now watch the video below to learn more about static electricity.
Lesson 4: What can Static Electricity do?
How to Move Things Without Touching Them.
Introduction
So far we have seen how static electricity can make your hair stand on end, balloons stick to walls and even move a tin can without touching it. however, did you know that the attraction between protons and electrons can also make clothes stick together in the dryer? When you dry clothes in the dryer, different fabrics rub together, and electrons from a cotton sock (for instance) may rub off onto a polyester shirt. That's why clothes sometimes stick together and make sparks when you pull them apart. You may have used anti-static sheets in your dryer. As these sheets bounce around with your clothes, they add a uniform anti-static coating to the fabric. Rather than cotton rubbing against polyester, you've got the anti-static coating on the cotton rubbing against the anti-static coating on the polyester. No electrons rub off-and you don't get any static cling.
Xerox machines also use static electricity to make copies. When you rub a balloon on your head, the balloon is charged with electricity. Inside a Xerox machine is a plastic drum that is also charged. When you put a piece of paper on the glass, a copy of it goes onto the drum. Where there were dark places on the paper, the static charge on the drum attracts the black plastic toner powder. Then the powdered places go onto a blank piece of paper, and the paper is heated. The toner melts and makes black letters on the new piece of paper. That's how amazing and useful static electricity can be.
In this lesson you will see how static electricity can even make a pencil spin on a bottle top.
So far we have seen how static electricity can make your hair stand on end, balloons stick to walls and even move a tin can without touching it. however, did you know that the attraction between protons and electrons can also make clothes stick together in the dryer? When you dry clothes in the dryer, different fabrics rub together, and electrons from a cotton sock (for instance) may rub off onto a polyester shirt. That's why clothes sometimes stick together and make sparks when you pull them apart. You may have used anti-static sheets in your dryer. As these sheets bounce around with your clothes, they add a uniform anti-static coating to the fabric. Rather than cotton rubbing against polyester, you've got the anti-static coating on the cotton rubbing against the anti-static coating on the polyester. No electrons rub off-and you don't get any static cling.
Xerox machines also use static electricity to make copies. When you rub a balloon on your head, the balloon is charged with electricity. Inside a Xerox machine is a plastic drum that is also charged. When you put a piece of paper on the glass, a copy of it goes onto the drum. Where there were dark places on the paper, the static charge on the drum attracts the black plastic toner powder. Then the powdered places go onto a blank piece of paper, and the paper is heated. The toner melts and makes black letters on the new piece of paper. That's how amazing and useful static electricity can be.
In this lesson you will see how static electricity can even make a pencil spin on a bottle top.
You can try this experiment at home.
Equipment Needed
How Does this Science Experiment Work?The pencil turns because, basically, you pile up electrons on one thing and use them to attract the protons in something else. When you rub a balloon on your hair, it ends up loaded with electrons. Those electrons can attract the protons in a pencil.
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Method
Now watch the video below to learn more about static electricity.
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Lesson 5: Can you make an electric circuit?
Introduction
If you've ever sat watching a thunderstorm you'll have some idea of the power of electricity. A bolt of lightning is a sudden, massive surge of electricity between the sky and the ground beneath. The energy in a single lightning bolt is enough to light 100 powerful lamps for a whole day or to make a couple of hundred thousand slices of toast! Electricity is a type of energy that can build up in one place or flow from one place to another. When electricity gathers in one place it is known as static electricity (the word static means something that does not move); electricity that moves from one place to another is called current electricity or electric current. When electrons move, they carry electrical energy from one place to another. A lightning bolt is one example of an electric current, although it does not last very long.
Electric currents are also involved in powering all the electrical appliances that you use, from washing machines to flashlights and from telephones to MP3 players. These electric currents last much longer. For an electric current to happen, there must be a circuit. A circuit is a closed path or loop around which an electric current flows. A circuit is usually made by linking electrical components together with pieces of wire cable. Thus, in a flashlight, there is a simple circuit with a switch, a lamp, and a battery linked together by a few short pieces of copper wire. When you turn the switch on, electricity flows around the circuit. If there is a break anywhere in the circuit, electricity cannot flow. If one of the wires is broken, for example, the lamp will not light. Similarly, if the switch is turned off, no electricity can flow. This is why a switch is sometimes called a circuit breaker.
If you've ever sat watching a thunderstorm you'll have some idea of the power of electricity. A bolt of lightning is a sudden, massive surge of electricity between the sky and the ground beneath. The energy in a single lightning bolt is enough to light 100 powerful lamps for a whole day or to make a couple of hundred thousand slices of toast! Electricity is a type of energy that can build up in one place or flow from one place to another. When electricity gathers in one place it is known as static electricity (the word static means something that does not move); electricity that moves from one place to another is called current electricity or electric current. When electrons move, they carry electrical energy from one place to another. A lightning bolt is one example of an electric current, although it does not last very long.
Electric currents are also involved in powering all the electrical appliances that you use, from washing machines to flashlights and from telephones to MP3 players. These electric currents last much longer. For an electric current to happen, there must be a circuit. A circuit is a closed path or loop around which an electric current flows. A circuit is usually made by linking electrical components together with pieces of wire cable. Thus, in a flashlight, there is a simple circuit with a switch, a lamp, and a battery linked together by a few short pieces of copper wire. When you turn the switch on, electricity flows around the circuit. If there is a break anywhere in the circuit, electricity cannot flow. If one of the wires is broken, for example, the lamp will not light. Similarly, if the switch is turned off, no electricity can flow. This is why a switch is sometimes called a circuit breaker.
You can try this experiment at home.
Equipment Needed
A circuit is a complete path around which electricity can flow.
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Method
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Now watch the video below to learn more about electrical circuits.
Lesson 6: Which materials conduct electricity?
Introduction
Water is a very good electrical conductor. This is why it is extremely dangerous to mix electricity and water, and to use electrical items near to water. However, not all materials are able to conduct electricity. Some materials are better than others. Metal is a good conductor of electricity. This is why electrical wires are made of copper. Some materials will not conduct electricity at all and these materials are known as insulating materials or insulators. Plastic is a good insulator which is why copper wiring is usually coated in plastic. If you hold an electrical wire, the plastic stops the electricity from leaving the wire and entering your body. In this lesson we will learn more about conductors and insulators.
Water is a very good electrical conductor. This is why it is extremely dangerous to mix electricity and water, and to use electrical items near to water. However, not all materials are able to conduct electricity. Some materials are better than others. Metal is a good conductor of electricity. This is why electrical wires are made of copper. Some materials will not conduct electricity at all and these materials are known as insulating materials or insulators. Plastic is a good insulator which is why copper wiring is usually coated in plastic. If you hold an electrical wire, the plastic stops the electricity from leaving the wire and entering your body. In this lesson we will learn more about conductors and insulators.
You can try this experiment at home.
Equipment Needed
A conductor is a material that allows electricity to flow through it.
An insulator is a material that does not allow electricity to flow through it.
Now watch the video and read the facts to learn more about electrical circuits.
2. Examples of good conductors
Aluminum, copper, gold, water, and people are examples of conductors. It is why electricity producers use copper and aluminum wires to carry power from generating plants to consumers. Conductors also allow heat energy to pass through them. |
Method
Facts
1. Conductors and Insulators
Think of it this way: A conductor is like a tube with many loose balls. If you push one other loose ball into one end, there will be a knock-on effect until one pops out at the other end. Conductivity is the ability of a material to conduct electricity. Such a material is said to have high conductivity. 3. Examples of good insulators
An insulator is a material that does not allow electricity to pass through them.Rubber, plastics, wood, and paper are all great examples of insulators. These materials are also poor conductors of heat energy. |
Lesson 7: Can you make an electromagnet?
Introduction
As an electric current flows through an insulated wire it creates an electromagnetic field. If you wrap wire around a nail this causes the nail to act like a magnet. This kind of magnet is known as an electromagnet. An electromagnet is useful as it can be switched on, or off, as you wish. Such magnets are useful in things like electric bells. They are also used in scrap metal yards to pick up big pieces of metal and to drop them again. They are also used in switches.
You can try this experiment at home.
What You Need
Method
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An electromagnet is a piece of iron encircled by a coil of wire through which an electric current is passed to magnetize the iron.
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What happens?
- If you disconnect one end of the wire from the battery what happens?
- Disconnect the battery at both ends when you have finished - allowing it to cool.
- This electric current creates a magnetic field that magnetizes the nail. When the current flows through the wire it produces a magnetic field.
After carrying out the above experiment, or reading it, please watch the video on the right.
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Lesson 8: Can I Demonstrate thatWater Conducts Electricity?
Introduction
“Don’t touch a switch with wet hands!” We were all taught that since we were very young children. It does seem like water can conduct electricity and that is why we shouldn’t touch any electrical outlet, or switches, if our hands are not dry. But does water really conduct electricity? And can salt water conduct electricity too? Which is best at conducting electricity, tap water or salt water? How can we prove it without getting killed or electrocuted? Let’s find out by doing a simple controlled experiment.
You can try this experiment at home.
Method
1. Fill the small container with tap water.
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A controlled experiment is a test done twice with exactly the same conditions and variables except for one.
That one varied element is called an experimental control. Here water is the experimental control. |
What happens?
- Using tap water, you should be able to complete the circuit and light the bulb.
- When you dissolve salt in the water your bulb should get brighter. This is because salt water is a better conductor than ordinary tap water.
Conclusion
In this controlled experiment, water is the experimental control. Everything else in the experiment stayed the same. So we can conclude that the difference in the outcome is caused by the control, i.e. the water. We proved that tap water can conduct electricity and that salt water is even better at conducting electricity. So, this is why you should never mix water and electricity and you should never go swimming outdoors in a thunderstorm. If lightning strikes the water you will almost certainly be electrocuted!
In this controlled experiment, water is the experimental control. Everything else in the experiment stayed the same. So we can conclude that the difference in the outcome is caused by the control, i.e. the water. We proved that tap water can conduct electricity and that salt water is even better at conducting electricity. So, this is why you should never mix water and electricity and you should never go swimming outdoors in a thunderstorm. If lightning strikes the water you will almost certainly be electrocuted!
Lesson 9: Can I Make Two Bulbs Shine Equally Brightly?
Introduction
Parallel Circuits In a parallel circuit, there is more than one resistor (bulb) and they are arranged on many paths. This means electricity (electrons) can travel from one end of the cell through many branches to the other end of the cell. This means that the electricity is able to flow equally through each bulb. In the example on the right it means the bulbs should be of equal brightness. The great thing about parallel circuits is that, even when one resistor (bulb) burns out, the other bulbs will work because the electricity is not flowing through one path. Think of all the light bulbs in your home. If one bulb burns out, the other bulbs in the rooms still work. Another great thing is that the bulbs in a parallel circuit do not dim out like the case in series circuits. This is because the voltage across one branch is the same as the voltage across all other branches.
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Series Circuits A series circuit is one that has more than one resistor, but only one path through which the electricity (electrons) flows. From one end of the cell (battery), the electrons move along one path with no branches, through the resistors, to the other end of the cell. All the components in a series circuit are connected end-to-end. A resistor in a circuit is anything that uses some of the power from the cell. In the example on the left, the resistors are the bulbs. In a series circuit, the components are arranged in a line, one after the other.
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You can try this experiment at home.
What You Need
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Method
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What Did You Learn?
When bulbs are in a series circuit, which bulb is brightest?
When bulbs are in a parallel circuit, which bulb is brightest? |
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After carrying out the above experiment, or just reading it, please watch the video on the right. You only need to watch the first five minutes.
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Lesson 10: What is an Open and Closed Circuit?
Introduction
You need a closed path, or closed circuit, to get electric current to flow. If there’s a break anywhere in the path, you have an open circuit, and the current stops flowing — and the metal atoms in the wire quickly settle down to a peaceful, electrically neutral existence.
Picture a gallon of water flowing through an open pipe. The water will flow for a short time but then stop when all the water exits the pipe. If you pump water through a closed pipe system, the water will continue to flow as long as you keep forcing it to move. Open circuits are often created by design. For instance, a simple light switch opens and closes the circuit that connects a light to a power source. When you build a circuit, it’s a good idea to disconnect the battery or other power source when the circuit is not in use. Technically, that’s creating an open circuit.
A flashlight that is off is an open circuit. In the flashlight shown here, the flat black button in the lower left controls the switch inside. The switch is nothing more than two flexible pieces of metal in close proximity to each other. With the black button slid all the way to the right, the switch is in an open position and the flashlight is off.
You can try this experiment at home.
Make a Simple Maze Game
- Make a simple electric circuit using the battery and a bulb.
- Connect one of the wires to a thin wire and stretch it between two cups to make a wire maze.
- Connect the other wire to a coiled piece of wire.
- Try to run the coiled wire the complete length of the wire maze.
- If the wires touch the light should switch on.
- Play a game to see who can not cause the light to switch on.
- If the game is too easy put twists and turns in the stretched wire or make the coil smaller.
When the coiled wire touches the wire maze you have made a closed circuit so the light and buzzer should work.
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When the coiled wire is not touching the wire maze you have made an open circuit so the bulb and buzzer won't work.
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After carrying out the above experiment, or just reading it, please watch the video on the right.
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