SCIENCE 4 Q3 Lesson 8 ELECTRICITY AND MAGNETISM

SCIENCE 4 Q3 Lesson 8 ELECTRICITY AND MAGNETISM

By Maritess Jacinto

Following God

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"For the kingdom of God is not a matter of talk but of power.

1 Corinthians 4:20

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At the end of this lesson, using your knowledge about electricity, I you will be able to:

 ·  define concepts related to electricity and magnetism, cite examples of how they are used,

​·  electricity and magnetism safely and economically.

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​The ancient Greeks had observed that a piece of amber rubbed with a cloth could attract bits of straw and wool.

In the 1500s, an English physician found out that other substances such as sulfur, sealing wax, and glass showed a similar tendency to attract objects when rubbed, and therefore named these substances "electrics" after the Greek word for amber, electron.

 

​Lightning can be one of the most terrifying of nature's phenomena. In the 1700s, Benjamin Franklin, the freedom-fighter, statesman, writer, and scientist, set out to prove that it was a form of electricity. Fortunately, he survived the experiment that had him flying a kite with a key attached to the string in a lightning storm. Electricity then was a barely understood energy form. You should not try to duplicate his experiment-IT IS EXTREMELY DANGEROUS! A later experimenter tried it and died of electrical shock from the lightning that struck the key.

Energy in the form of moving electrons is called electricity.

 Perhaps you have experienced going down a slide, then touching someone on the ground with a fingertip, and getting a jolt.

You may even have seen and heard an actual spark fly!

What you experienced is a transfer of static electricity or stored electricity.

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​What is electricity?​

​You have learned that atoms have tiny parts called electrons. Electrons have a negative charge.

They also have protons in the nucleus. Protons have a positive charge. These charges are equal in strength. Usually, atoms have as many electrons as protons. Therefore, they are balanced or neutral.

Unlike charges are to each other, while like charges repel.

After several trips down the slide, your body gains electrons and stores them. You become negatively charged. When you touch someone who has not been sliding and is positively charged, whaml -- electrons from your fingers jump across to the other person, giving both of you a jolt.

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Static electricity is also involved when after you have been squirming in a plastic chair, your hair begins to stand on end and stick to the chair. If you break a sugar cube in complete darkness, you may see a small green flash that shows static electricity was transferred.

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If your car is struck by lighting and we have to leave your car,

JUMP OUT! DO NOT ALLOW ANY PART OF YOUR BODY TO TOUCH THE CAR AND THE GROUND AT THE SAME TIME

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Static electricity is usually made up of small charges. No one has yet found a way to use lightning because it is so unpredictable.

The electricity we use has to be in a form that can be controlled, to be turned on or off, and in safe and useful amounts.

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Multiple Choice

Lightning occurs because ___.

• the negative charges at the bottom of clouds are attracted to the positive charges on the ground.

• the positive charges at the bottom of clouds are attracted to the negative charges on the ground.

• the positive and negative charges inside clouds are attracted to each other

• All of these reasons are correct.

​Electrical wiring has to be covered with insulating materials, otherwise we would not be safe using electricity.

Multiple Choice

The buildup of charges on an object is called:

• positive charge
• static charge
• negative charge
• static discharge

​Electricity, to be useful, however, has to be able to flow continuously. The continuous flow of electrical energy is called a current.

To keep electrons moving, they have to travel through a material that is a conductor, one that has low resistance, and therefore allows electrons to transfer from place to place.

(Low resistance is the property that allows energy like heat or electricity to move easily through a material.)

Metals like copper are good conductors.

Electricity flows easily through a copper wire.

Materials that do not allow electrons to move freely are called insulators.

Wood, rubber, plastic, and air are insulators.

Multiple Choice

This allows energy to flow.

• conductor

• insulator

Multiple Choice

This does not allow energy to flow.

• insulator

• conductor

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​​Electrical wiring has to be covered with insulating materials, otherwise we would not be safe using electricity

How is electricity produced?

Some of the electricity we use comes from a source we call an electric cell or battery. Flashlights, toothbrushes, and clocks use batteries. Alessandro Volta made the first electric cell using a strip of paper soaked in salt water sandwiched between a strip of zinc and a strip of copper. Wires that connected the two metals kept the electrons flowing.

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​How is electricity produced?

Some of the electricity we use comes from a source we call an electric cell or battery. Flashlights, toothbrushes, and clocks use batteries. Alessandro Volta made the first electric cell using a strip of paper soaked in salt water sandwiched between a strip of zinc and a strip of copper. Wires that connected the two metals kept the electrons flowing.

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The path electrical energy travels is called a circuit. Electricity has to flow through a closed circuit. A closed circuit has three parts: 1) the source, which may be a battery or the electrical outlet; 2) the wires that connect the source to an object or appliance (and wires that reconnect it back to the source); and 3) the object or appliance that electricity flows through

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If you connect a wire to the positive end of a battery, and another wire to the negative end of a battery, and then connect the wire ends to a light bulb, the bulb would light up because electricity can keep moving when the circuit is complete or closed.

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​If the connection were broken at any point, then the bulb would not light up because electricity cannot flow in an open circuit.

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Multiple Choice

An open circuit allows charges to flow.

• True

• False

Multiple Choice

Which parts are needed to complete a simple circuit lighting a lightbulb?

• wire, battery, lightbulb

• wire, buzzer, lightbulb

• wire, battery, buzzer

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​In a series circuit, the lights are all part of the same path, and turn on and off all at the same time. If one is removed, or turned off, then the circuit opens, and none of the lights would work.

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​A series circuit is not practical to have all throughout the house, because all your appliances would have to be working at the same time.

 In a parallel circuit, each light and outlet is wired separately into the main source. This way, you can turn lights and appliances on or off as needed.

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​Electricity that comes into our homes is generated by a power plant. The power plant gets its energy from one of the following sources:

1. Hydroelectric power

2. Geothermal power

3. Coal

4. Petroleum

5. Wind power

6. Solar power

7. Nuclear power (not available in the Philippines)

A hydroelectric power plant uses the kinetic energy of waterfalls (such as Maria Cristina Falls in Lanao) to turn special wheels called turbines that run a generator. A generator produces the electricity that flows along wires to our homes.

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A geothermal plant uses steam from hot springs. Hot springs come from ground water heated by magma of nearby volcanoes. The Tiwi power plant in Albay in the Bicol region is an example.

 

Other power plants use coal where this is plentiful. This is possible in Cebu, Philippines, which has a coal mining district.​

​ Other places use petroleum in their power plants because it is the most easily transportable and available (although expensive) alternative.

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Solar-generated and wind-generated electricity are still small localized attempts to use alternative sources of energy.

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Multiple Choice

This type of renewable energy converts the power of the wind to electricity.

• steam engines
• solar power
• wind turbines
• nuclear power

Multiple Choice

Hydroelectric plants perform which type of energy conversion?

• Water to Electricity
• Electricity to Water
• Wind to Electricity
• Wind to Chemical

Multiple Choice

Which renewable resource gets its direct energy from the sun? 

• Geothermal
• Solar
• Wind
• Hydrogen

​What is magnetism?

Magnetism is a force that causes certain metals to have the ability to attract other metals. Iron and steel can be strongly affected. Cobalt and nickel are only weakly affected. Copper, aluminum, and non-metals are not affected this force

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​Magnetism can occur naturally, as in a stone called magnetite. Magnets can also be produced in a variety of shapes, such as the horseshoe, bar, discs, flat sheets, and even strip magnets-by-the meter.

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The area around a magnet where the effect of a magnet is detected is called its magnetic field. The shape of the magnetic field varies slightly depending on the shape of the magnet. But whatever their shape, all magnets have the same properties. One of these properties is that magnets have the greatest attractive force at their ends, called the poles. These poles are called the North pole and the South pole.

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​ If you have two magnets, touch one pole of a magnet to one of the poles of the other magnet.

What happens?

One possibility is that the magnets will be attracted, move toward each other, and stick. This means that one pole has found the opposite pole-north meets south.

The other possibility is that the poles will be repelled and move away. This means that similar poles were brought together.

These two situations show you a basic principle of magnetism: Opposite poles attract, like poles repel.

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If you try to push like poles together, you will feel the push a magnet can give.

You will notice that magnets can make objects move.

This ability also gives magnets another unique ability: pointing out direction.

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Try tying a string around a magnet, taping the string in place to keep the magnet balanced. If allowed to swing freely, the poles will eventually point approximately north and south-called the magnetic North Pole and magnetic South Pole.

The same pole will always point north and the other pole will always point south. Magnetic north is about 1,600 kilometers from the place on the map called the North Pole.

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Multiple Choice

Which of these is attracted to a magnet?

• iron nail
• copper penny
• piece of paper
• notebook

Multiple Choice

What do you call it when two magnets come together?

• attract
• iron
• poles
• repel

Multiple Choice

The two poles on a magnet are

• north and east
• north and west
• south and north
• south and west

Multiple Choice

If you placed the south pole of one bar magnet near the south pole of another bar magnet, the two magnets would __________ each other.

• attract
• cancel
• repel
• discharge

Multiple Choice

A magnet would be attracted to a rubber band.

• true
• false

Magnets can be used to generate electricity. If a magnet is moved near a wire, electricity through it. If you kept the magnet stationary and moved the wire, electricity runs through it too. Motion, either of the magnet or of the wire, is needed to generate electricity.

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​How are electricity and magnetism related?​

Generators at power plants the energy of waterfalls, coal, natural gas, petroleum, or geothermal energy to move large magnets and loops of wire to generate electricity.

Electricity can be used to make magnets. You can make an electromagnet by winding a wire around a nail many times, and connecting the wire ends to the terminals (positive and negative ends) of a battery or dry cell.

(DO NOT PUT THE WIRES INTO A WALL SOCKET OR ANY ELECTRICAL OUTLET.) The more coils there are, the stronger the magnet will be. As long as you have a closed circuit, electricity will flow through the wire, the nail is magnetized and will pick up metal objects.

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Multiple Choice

Some electrical devices use motors. Motors have magnet inside them.

• True

• False

Multiple Choice

Magnet is only used for electrical devices.

• True

• False

Multiple Choice

Magnet can be used to hold things together.

• True

• False

Multiple Choice

Magnet is use to attract non-magnetic materials at waste factory.

• True

• False

Multiple Choice

Magnet can be used as a tight seal on fridge doors.

• True

• False