Electromagnets Free Science Lessons
Lalo Scalf
One of the main principles behind electricity and magnetism is that the movement of charged particles in the same direction will result in a magnetic force. When a wire is hooked up to a battery, negatively charged particles (electrons) flow away from the negative terminal of the battery toward the positive end, because opposite charges attract each other, while like (similar) charges repel each other. This flow of electrons through wire is electric current, and it produces a magnetic force. In a magnet, atoms are lined up so that the negatively charged electrons are all spinning in the same direction. Like electric current, the movement of the electrons creates magnetic force. The way the atoms are lined up creates two different poles in the magnet, a north pole and a south pole. As with electrical charges, opposite poles attract each other, while like poles repel each other.
Your magnetized paperclip was a very weak temporary magnet, but an electromagnet is a temporary magnet that can be very strong. It consists of tightly coiled wire (called a solenoid) wrapped around a ferromagnetic core. When the wire is hooked up to a battery and an electrical current flows through it, it creates a magnetic force. This magnetizes the ferromagnetic core, and the two magnetic forces together create a strong magnet. Industrial electromagnets can lift cars and other huge objects! As soon as the electric current stops flowing through the wire, the electromagnet loses its magnetism.
Print out this page on a sheet of heavy paper or cardstock. Kids can color the pictures and cut out the squares to make a matching game. Half of the squares show a way to use solar energy as an alternative to the picture shown on the other squares. Place all the...
Spring break is here! What will you do with your time off? Perhaps you're looking forward to a family vacation, or a few days of down time at home. Either way, find a quick and easy project that's sure to put a sparkle in the eye of any science lover, or win over a...
Use the Sink or Float Worksheet with the "Sink or Float?" science project to encourage kids to make predictions, perform tests, and record their results. This project is perfect for indoor discovery - especially in colder months! Put a towel under a large container of...
By the end of this comprehensive lesson plan about the electromagnetic spectrum, students will be able to explore how different the electromagnetic spectrum's different wavelengths are used to gain information about distance and properties of objects in the universe. Students will also learn how to properly to interpret the electromagnetic spectrum. Each of our lessons is designed using the 5E method of instruction to ensure maximum comprehension by the students. This well-thought out unit does the heavy lifting, giving teachers easy-to-implement, highly engaging lesson plans.
Afterwards, the engagement activity will continue with a Think-Pair-Share brainstorm activity. Students will look at a PDF with a number of quotes from astronomers. Students will then partner up to read and then summarize each quote. Finally, students will then answer questions on a sheet of paper. Once the teacher has done all this, they'll help to clear any up misconceptions their students may still have. A common but major misconception, for is example, is that there's more than one star within our solar system, or that isn't possible to determine the composition of far away stars.
With nine stations in total, you can introduce the electromagnetic spectrum to your middle school students in a variety of ways! Four of these stations are considered input stations where students will learn new information about the electromagnetic spectrum, and four of the stations are output stations where students will be demonstrating their mastery of the lesson's material. A bonus station offers challenges for your early finishers and independent learners. You can read more about how I set up the station labs here.
At this station, students will be watching a five-minute video about the electromagnetic spectrum. The video will explain to students how the spectrum works and the many different waves that we experience every single day. Students will then answer three questions related to the video and record their answers on their lab station sheet.
This station will provide students with a one-page reading about the electromagnetic spectrum. Afterwards, students will be asked four questions about the reading about topics including vocabulary, alternate titles, fill in the blanks, and what kinds of waves eyes detect.
The research station will allow students to go online and watch an interactive presentation about the electromagnetic spectrum. Students will then be asked to answer two questions based on what they learned.
The Organize It station allows your students to use a manipulative to ensure their understanding of the electromagnetic spectrum. Students will use cards to match descriptions of wavelengths to correctly identify the wavelength.
Students who can answer open-ended questions about the lab truly understand the concepts that are being taught. At this station the students will be answering three questions, like describing low and high-frequency wavelengths, defining vocabulary in their own words, describing how scientists use the electromagnetic spectrum to find properties of distant stars.
The Assess It station is where students will go to prove mastery over the concepts they learned in the lab. The questions are set up in a standardized format with multiple choice answers. Some questions will ask students to compare wavelengths, frequencies, and why scientists use them.
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An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Electromagnets are widely used as components of other electrical devices, such as motors, generators, electromechanical solenoids, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment. Electromagnets are also employed in industry for picking up and moving heavy iron objects such as scrap iron and steel.[2]
Danish scientist Hans Christian rsted discovered in 1820 that electric currents create magnetic fields. In the same year, the French scientist Andr-Marie Ampre showed that iron can be magnetized by inserting it in an electrically fed solenoid.
British scientist William Sturgeon invented the electromagnet in 1824.[3][4] His first electromagnet was a horseshoe-shaped piece of iron that was wrapped with about 18 turns of bare copper wire. (Insulated wire did not then exist.) The iron was varnished to insulate it from the windings. When a current was passed through the coil, the iron became magnetized and attracted other pieces of iron; when the current was stopped, it lost magnetization. Sturgeon displayed its power by showing that although it only weighed seven ounces (roughly 200 grams), it could lift nine pounds (roughly 4 kilos) when the current of a single-cell power supply was applied. However, Sturgeon's magnets were weak because the uninsulated wire he used could only be wrapped in a single spaced-out layer around the core, limiting the number of turns.
Beginning in 1830, US scientist Joseph Henry systematically improved and popularised the electromagnet.[5][6] By using wire insulated by silk thread and inspired by Schweigger's use of multiple turns of wire to make a galvanometer,[7] he was able to wind multiple layers of wire onto cores, creating powerful magnets with thousands of turns of wire, including one that could support 2,063 lb (936 kg). The first major use for electromagnets was in telegraph sounders.
The magnetic domain theory of how ferromagnetic cores work was first proposed in 1906 by French physicist Pierre-Ernest Weiss, and the detailed modern quantum mechanical theory of ferromagnetism was worked out in the 1920s by Werner Heisenberg, Lev Landau, Felix Bloch and others.
A common tractive electromagnet is a uniformly-wound solenoid and plunger. The solenoid is a coil of wire, and the plunger is made of a material such as soft iron. Applying a current to the solenoid applies a force to the plunger and may make it move. The plunger stops moving when the forces upon it are balanced. For example, the forces are balanced when the plunger is centered in the solenoid.
The maximum pull is increased when a magnetic stop is inserted into the solenoid. The stop becomes a magnet that will attract the plunger; it adds little to the solenoid pull when the plunger is far away but dramatically increases the pull when they are close. An approximation for the pull P is[11]
Some improvements can be made on the basic design. The ends of the stop and plunger are often conical. For example, the plunger may have a pointed end that fits into a matching recess in the stop. The shape makes the solenoid's pull more uniform as a function of separation. Another improvement is to add a magnetic return path around the outside of the solenoid (an "iron-clad solenoid").[11][12] The magnetic return path, just as the stop, has little impact until the air gap is small.
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