Electricity and Magnetism

Transcription

1 Electricity and Magnetism This is a high-energy demonstration that explores the positives and negatives of static electricity. Audience members participate in simple and not-so-simple experiments, utilizing items as common as Rice Krispies and as extraordinary as a high-voltage generator. These supercharged experiments are sure to attract a lot of attention and will prove to be a hair-raising experience! Recommended Grade Level: 2-5

2 Electricity and Magnetism Program Information NJ Standards: 2009 NJCCCS: A: Understand Scientific Explanations B: Generate Scientific Evidence through Active Investigations D: Participate Productively in Science A: Properties of Matter C: Forms of Energy D: Energy Transfer and Conservation D: Energy Transfer and Conservation D: Energy Transfer and Conservation E: Forces and Motion E: Forces and Motion E: Forces and Motion Learning Objectives: By the end of the presentation, the audience will know: The basic atomic structure of an atom is comprised of 3 parts Charged portions of an atom are responsible for electrical phenomenon A conductor allows for a flow of charge, an insulator does not Magnetism is caused by the same parts of an atom as electricity Flowing charge creates a magnetic field and a moving magnetic field can cause charge to flow Program Overview: Electricity is something that people use every day. Yet few people understand what electricity is or where it comes from. This program presents the relationship between electricity and magnetism through the use of demonstrations and hands on activities. Special Instructions: Will need access to tables and electricity. See next page

3 Thank you for reserving...electricity and Magnetism There are just a few things we will need: 1. Parking: Safe, legal parking with easy access to our vehicle must be provided. 2. Power We will need access to two normal (grounded) 110-volt electrical outlets. Please be sure outlets in the performance area are working and unobstructed. 3. Space Our program requires a regular size classroom. If this show is being booked as an assembly program, please be advised that we will need one long table set up ahead of time (minimum size 2 feet wide x 6 feet long). Please be advised that this space must be available to us 45 minutes prior to the scheduled start time for set-up and 30 minutes following the conclusion for break down. For safety reasons, we cannot have students in the area while we are setting up or breaking down the programs. 3. Equipment No additional equipment needed. 4. Restrictions The audience size is limited to a maximum of 30 students per workshop. 5. Directions If you know that the online driving directions to your location are inaccurate, please see the next page. Please contact us at

4 if any of these outlined criteria present an issue. Our Traveling Science Educators normally use MapQuest for directions. Most times the directions are accurate. However: If directions from online services to your venue are inaccurate or difficult to understand please use this form to clearly print or type directions to your location. If there are any special instructions we must follow once we get to your location please note them below. Please use this form only. Do not substitute! Venue (program site): Contact name: Date of program: Telephone: Estimated driving time from Liberty Science Center: Hours Minutes To ensure our timely arrival we MUST know how long it takes to reach you. Directions Must start from Exit 14B of the N.J. Turnpike or the Holland Tunnel Please return via mail: Or by fax: Liberty Science Center Traveling Science Program 222 Jersey City Boulevard Jersey City, NJ Attn: Traveling Science Program In case of snow day cancellation, call as early as possible. Please reschedule for the next working day at

5 Please return this form no later than two weeks prior to our visit. Electricity and Magnetism Pre-visit Activity Guide This packet contains some simple classroom activities using everyday, inexpensive (or even free!) items. Please feel free to duplicate these pages as needed - they are sent on plain white paper to ensure the best quality of reproduction. We suggest that these activities be conducted before our visit in order to familiarize students with some of the concepts we will explore together during our Electricity and Magnetism Classroom Workshop. However, they may also be used after our visit to serve as a reinforcement of the concepts covered in the program. It is entirely at the discretion of each teacher to use these activities if and when he/she chooses, and whether or not all of the activities are appropriate for his/her class. If you have questions about any of the enclosed activity procedures, feel free to call our Science Educators Associate Director at We thank you for your interest in our program and eagerly look forward to visiting your school.

6 Experiments With Electricity and Magnets Opposite charges attract. The same kinds of charges repel one another. Since all matter is electrically charged, it is possible to experiment with static electricity using everyday things. Note: Be sure to remind your students that while working with static electricity in these experiments is very safe; experimenting on their own with current electricity - the kind in batteries and wall outlets - could be not only dangerous but downright deadly! Everything in the world is made up of atoms. They are the one of the smallest pieces of an element. Atoms are made up of three different kinds of particles: electrons, protons, and neutrons. Protons and electrons carry electrical charge. Neutrons are electrically neutral, hence the name. At the center of each atom is a nucleus, housing neutrons and positively charged protons. One or more fields of negatively charged electrons orbit the nucleus in what are called shells. Tin Can Racers Materials: Clean, empty soda cans Balloons Tape to mark the start and finish lines on the floor Dry weather! Procedure: 1. Place the soda cans on the starting line. 2. Blow up balloons and charge them by rubbing it on hair, a sweater or on something wool or flannel. 3. On the starter s mark students hold balloons near the soda cans and the static charge attracts the can, starting it rolling. How fast can they make it go? Who will get to the finish line first? If they touch the balloon to the can, it will discharge the electricity in the balloon and that can will be disqualified.

7 Static Horse Race Materials: Tissue paper Hard plastic combs Clean, dry hair, free of styling products Scissors Procedure: Cut small horses from folded pieces of paper so that they will stand on a table. Repeatedly, run the comb through hair. Bring the combs near the horses, And they re off! Making Breakfast More Attractive You know that several cereals claim to be "iron fortified." How do they do that? By adding some finely powdered iron (like small iron filings) to the cereal as it is being made! To prove this, simply do the following: Materials: Procedure: Half a serving of cereal that has a large percentage of the RDA (Recommended Dietary Allowance) for iron Water Bowl A very strong magnet 1. Mix up the water and cereal so that it is a watery slurry, not very thick. Take a strong magnet and place it into an inside-out zip-lock bag. (The purpose for the bag is to keep the surface of the magnet free from iron particles which are very difficult to remove.) 2. Move the bagged magnet around in the slurry of the cereal. 3. After a minute, take the magnet and its plastic bag out of the slurry, and examine it to see small, dark specks attached to the plastic at the magnet. This is metallic iron.

8 4. You can now turn the bag outside in and carefully remove the magnet from the zip-lock bag. This will keep the iron filings inside the bag. Unfortunately, our bodies can not absorb metallic iron very well, so this really does not help with our intake of iron. It would be better to take a supplementary multi-vitamin/mineral pill which contains absorbable iron. Your body needs the iron to help form hemoglobin (the pigment in red blood cells responsible for transporting oxygen). Uses for Magnets There are hundreds and hundreds of uses for magnets. They can hold items onto the refrigerator door, but that s only the beginning. Magnets were first put to use to help navigate as they will always point in a North / South direction, no matter what the weather is. For the most part, magnets are used to hold, separate, control, convey and elevate products and to convert electrical energy into mechanical energy or convert mechanical energy into electrical energy. Here's a list of things around the house and in the car that use magnets or electromagnets to make them work. Have students generate their own lists first. Around the house: Headphones Stereo and computer speakers Telephone receivers Phone ringers Microwave tubes Doorbell ringer solenoid Refrigerator magnets Seal around refrigerator door Plug-in battery eliminators Floppy disk recording and reading head Audio and Video tape recording and playback head Credit card magnetic strip TV degaussing coil Computer monitor and TV deflection coil Computer hard drive recording and reading head Dishwasher water valve solenoid Shower curtain weights / attach to tub Power supply transformers

9 Motors for use in: CD and DVD spinner and head positioner Audio and VHS tape transport VHS tape loader Microwave stirring fans Kitchen exhaust fans Garbage disposal motor Dishwasher Pump Timer Refrigerator Compressor Ice maker dumper Sump pump Furnace Things in the Car: Starter motor Interior fan motor Electric door locks Windshield wiper motor Electric window motor Side-view mirror adjuster motor Exhaust fan Garage door opener Clothes washer pump, agitator and timer Clothes dryer timer and drum turner Bathroom exhaust fan Electric toothbrush Ceiling fan Pager or cell phone vibrator Clocks (not wind-up or LCD type) Computer cooling fans Floppy disk, CD and DVD spinner Hard disk spinner Can opener Audio tape or CD player motor Engine speed sensors Alternator Starter relay Windshield washer pump motor

10 The Electromagnet A coil of wire with an electric current flowing through it becomes a magnet. (This activity should be used after students have investigated circuits.) Materials: Wire cutter 22-gauge insulated wire, cut into 24-inch long strips Per Group: 3 inch long iron or steel bolt 24inch long 22-gauge insulated wire strip 2 D-cell batteries 2-3 alligator clips or tape 20 paper clips and other objects attracted to magnets Scissors to strip the wire Procedure 1. Wrap the wire in a tight, even coil around the bolt. Leave 3-4 inches of wire loose at each end. Keep wrapping the wire until you get to the end of the bolt. There may be as may as 3 or 4 layers of wire all the way up and down the bolt. 2. Attach one end of the wire to the positive (+) end of one of your batteries. Attach the other end of the wire to the negative end (-) of your battery pack. 3. Try to pick up one of the paper clips with your electromagnet. What happens? How many turns of the wire does it take to pick up a paper clip? Now, unhook one of the wires from the battery. Will your electromagnet pick up a paper clip now? What do you need flowing through the wire to make the iron bolt act like a magnet? How many paper clips will your electromagnet hold? Can you hang clips on both ends of the bolt? Why? What things are attracted to a permanent magnet, such as a refrigerator magnet? Are these the same things that are attracted to the electromagnet?

11 4. Make your electromagnet stronger. Try adding more batteries to your battery pack. Make sure all the batteries face the same direction in the circuit. Now how many paper clips will your electromagnet hold? 5. Use a different size battery ( A versus C.) Does this make a difference? Are there any differences between what the permanent magnet and the electromagnet can do? 6. After using the electromagnet, remove the iron nail or bolt. Can the nail still pick things up? Try dropping the nail or bolt a couple of times on the floor. How does this affect whether or not you can pick up any paper clips? Is an electromagnet a temporary magnet or a permanent magnet? Why is it a temporary magnet? What happens when the power is switched off? Is there still a magnetic charge? Why? For how long?

12 N Isn t Really North! / Make a Compass If we hold two bar magnets near each other, the "N" (North) pole of one magnet is attracted by the "S" (South) pole of another. Opposite poles attract. If we suspend a bar magnet by a thread, the "N" pole of that magnet will point... toward the Earth's north! But wait If opposites attract, shouldn't the "N" pole of a magnet point towards the "S" of the Earth? Like poles should repel, not attract! Either the N and S printed on all bar magnets is reversed, or the N or "S" on the Earth is backwards. Which is it? This problem has a simple solution. Physicists define "N-type" magnetic poles as being the north-pointing ends of compasses and magnets. This means that the magnetic pole found deep inside the northern hemisphere of the Earth is a southtype magnetic pole. The Earth's northern magnetic pole is an S! It has to be this way; otherwise it would not attract the N-pole of a compass. Make Your Own Compass The compass is a device we use to determine direction. In its simplest form, a compass is a magnetic needle that turns on a pivot. The Earth produces a magnetic field. This field, although weak, is sufficient to align iron and other paramagnetic* compounds such as a needle within it. By floating the needle on the cork, it can rotate freely and orient itself within the Earth's magnetic field, to point toward the north or south poles of the planet. *paramagnetic: having an induced magnetic field like the metal that becomes magnetized by the electromagnet. In fact, the compass was the first practical use humans found for magnetism. Early ships were wooden, so simple magnetic compasses came in handy. On long voyages, clouds or storms often obscured stars, which were the principle means of navigation at the time. The compass helped sailors stay the course.

13 Magnetic compasses point to magnetic north, which is located near the northern islands of Canada - not the North Pole. Did you know that the Earth s magnetic pole periodically reverses? It is unpredictable and nobody knows why, really. For a more detailed explanation : Magnetic north is determined by the magnetic fields of the Earth and moves a few miles from year to year. Our compass works because the iron in the pins becomes magnetized after being stroked with the magnet. It then aligns itself with the magnetic north pole and points north! Overview: Make a simple compass to find magnetic north, or south, depending on where you live. Materials: 1. Sewing needle about one inch long. Needles are sharp be careful! 2. Small bar magnet. Refrigerator magnets may work if you don't have a bar magnet. 3. A small piece of cork. 4. A small glass or cup of water in which to float the cork and needle. Procedure: 1. Your compass will work better if you first run a magnet over the needle a few times, always in the same direction. This action slightly 'magneties' the needle. Push the needle through a piece of cork. Cork from wine bottles works well. Cut off a small circle from one end of the cork, and drive the needle through it, from one end of the circle to the other, instead of through the exact middle a thimble might be helpful. 2. Float the cork and needle in the cup of water so the needle lies roughly parallel to the surface of the water. 3. Place your 'compass' on a still surface and watch what happens. The needle should come to point towards the nearest magnetic pole - north, in our case, in the northern hemisphere. 4. If you want to experiment further, try placing a magnet near your compass and watch what happens. How close/far does the magnet need to be to cause any effects?