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Share this course via email. Prerequisites Knowledge of Classical Mechanics at the level of 8. Multivariable Calculus. Interested in this course for your Business or Team? Train your employees in the most in-demand topics, with edX for Business. Purchase now Request Information.
About this course Electricity and Magnetism dominate much of the world around us — from the most fundamental processes in nature to cutting edge electronic devices. This course will require the use of calculus. Meet your instructors Massachusetts Institute of Technology. Peter Dourmashkin Senior Lecturer, Physics. Analia Barrantes Lecturer, Physics. The most common ferromagnetic metals are iron, nickel, and cobalt. Ferromagnetic material contains many tiny magnetic domains at the microscopic level. Each magnetic domain has its own tiny magnetic field with a north and a south pole.
Normally, these domains point randomly in all different directions, so all the tiny magnetic fields cancel each other out, and the overall material is not surrounded by a magnetic field. However, when a material is magnetized usually by putting it in a strong magnetic field , all of these tiny magnetic fields line up, creating an overall larger magnetic field.
How, exactly, the tiny magnetic fields are generated depends on how electrons move inside atoms. This is one example of how magnetism and electricity are connected. Magnets are fun and useful, but can also be dangerous if they are not handled properly. Small magnets should always be kept away from small children and pets, because they can cause serious injury if they are swallowed.
Very strong magnets, like neodymium magnets, can pull together with a very high force, pinching your fingers if they are caught in between. You should always keep magnets away from electronic devices, like computers and cell phones, and away from credit cards or any other card with a magnetic strip. This is because the data on these devices is often stored using magnetic recording, and can be erased when it comes close to a strong magnetic field.
If you are doing a Science Buddies project involving magnets, be sure to read the safety precautions for that specific project before you start. Click here for a list of science projects related to magnetism. Note: We recommend reading the section on Magnetism and watching our introductory video before you read the section about electromagnetism. The video includes a segment about electromagnets. Electricity and magnetism are very closely related.
Electricity, Magnetism, & Electromagnetism Tutorial
The study of both, and how they are connected, is called electromagnetism. This page is just a brief introduction to electromagnetism, and contains information you may find useful for Science Buddies projects. There are entire textbooks written about electromagnetism, though; this is just the beginning! One common example of the interaction between electricity and magnetism is an electromagnet. An electromagnet is a special type of temporary magnet that only generates a magnetic field when electric current is flowing you can learn more about electric current in the Current Electricity tab.
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This makes electromagnets very convenient because they can easily be turned on or off, and can create very strong magnetic fields. A single, straight wire with current flowing through it creates a circular magnetic field configuration, as shown in Figure The hand in Figure 15 represents the right-hand rule , used to predict the direction of the magnetic field induced or created by a current.
When you point the thumb on your right hand in the direction of current flow, your fingers curl in the direction of the magnetic field. If the current reverses direction, the magnetic field lines will also reverse direction.
Electricity, magnetism and the body: some uses and abuses.
A bigger current will produce a stronger magnetic field. However, even a strong current in a single wire does not make a very strong electromagnet. To make a much stronger electromagnet, you can wrap the wire into a coil , as shown in Figure The magnetic field near a coil of wire looks very similar to the magnetic field near a bar magnet. Can you figure this out using the right-hand rule explained above? Just like with a single wire, if the electric current reverses direction, the magnetic field around the coil will also reverse direction. To make an electromagnet even stronger, you can wrap the coil around a ferromagnetic core , as shown in Figure 17 refer back to the Magnetism tab to learn about ferromagnetic materials.
That way, when the electromagnet turns on, it magnetizes the core. The magnetic fields of the coil and the core then add up, creating an even stronger electromagnet. An electric current is nothing more than moving electric charges. Anytime an electric charge moves, a magnetic field is created. You might wonder if moving magnets or a changing magnetic field would create an electric current or get electric charges to move. The answer is yes, it can. This aspect of electromagnetism is often used to create electricity in electric generators.
You can learn more about the link between electromagnetism and generating electricity in some of the hands-on projects linked below. Click here for a list of science projects related to electromagnetism. Is the page formatted correctly with a pleasing appearance? I didn't see anything wrong; everything looks fine.
Is the writing clear? Did you find any typos or incorrect facts? Did you encounter any error messages, broken links, or other problems? The images are put in key positions that break up chunks of text, making it more pleasing to look at. The charts are also put in good places that the viewer is drawn to them. The writing is clear throughout the entire page.
There were no typos or incorrect facts that I could find. I also liked how vocab or important words were bolded so that the viewer could know that those words are important. I did not encounter any error messages, broken links, or anything else. The entire page was pretty smooth. All of the links to the specific parts worked well too. The only concern I have is the use of italics versus bold lettering. Are you using it to show emphasis or vocabulary words?
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It's used a little randomly on the Static Electricity page. I'm an elementary teacher with a background in English and a love for tech. I might be Merriam-Webster when it comes to grammatical errors, but I'm the Wikipedia of science facts! Some materials, called insulators, hold their electrons very tightly. You can take out the entire first sentence of Figure 1, since it's just reiterating what was in the paragraph.
This is ALSO called a static discharge. It is a good landing page for the topic intro, consistent with the rest of the website so users already know what to do and where to look next.
With respect to the Magnetism subpage itself. I have to say it is one of the simplest and concise I have seen on the web. It has all the elements complete with video, figures and not too much lengthy reading.
Using electricity to switch magnetism
This is really excellent. Not much verbage but that is a good thing for this page. No, all the links on the3 page worked as well. Everything looks fine. Very nice citations. The introduction is shorter than most other Science Buddies projects. Nothing wrong with it. Everything is nice and I might try this project! We recommend reading the tabs in order, but you can click on the links below to jump straight to a certain topic: Static Electricity Current Electricity Direct Current versus Alternating Current DC vs.
Accessed 23 Sep. Summary of Key Concepts Charged particles—often, negatively charged electrons—are the basis of electricity. Static electricity is the imbalance of positive and negative electric charges.
Opposite electric charges attract; like electric charges repel. Figure 1. Like electric charges two positive charges, as shown, or two negative charges repel each other, or push each other away, while opposite charges a positive and a negative charge attract, or pull toward each other. This figure shows what would happen if you had electrically charged balls hanging from strings. Two like charges push away from each other, and two opposite charges pull toward each other. Technical Note An atom that loses one or more electrons has more positive charges than negative charges electrons.
Coulomb C Current Amount of electric charge passing through an area per second. Ampere A Voltage Also called electric potential, or the "pressure" that makes current flow. Volt V Resistance How difficult it is for current to flow. Watt W. Technical Note: Direction of Electric Current Electrons, being small and light, move easily and create the bulk of electric current we encounter, like current received from wall sockets or produced by most batteries.
Figure 2. If the current is represented by a positive variable referred to as the conventional current, represented by a red arrow in the figure , the arrow representing the direction of current will point opposite to the movement of the electrons represented with a blue arrow. Figure 3. When conductive material connects the two terminals of a battery, electrons will flow from the negative to the positive terminal. The conventional current will point from the positive to the negative terminal. Technical Note: Energy Consumed Most of our appliances specify how much electric energy they require per second they are in use.
Summary of Key Concepts Current can only flow in a closed circuit of conductive material. In direct current DC , electrons all move in the same direction. In alternating current AC , electrons move back and forth with a specific frequency measured in hertz Hz.
Caution : Never plug a homemade circuit directly into a wall outlet; the alternating current from the wall outlet can harm you badly. Figure 4. Illustration of how electric current can move through a closed loop of conductive material left figure but stops flowing whenever the loop is broken right figure. This figure shows how a light bulb lights up when it is connected to a closed circuit.
Note the yellow arrows show the direction of the conventional current. Figure 5. In the case of direct current DC , the free electrons always collectively move in the same direction. Important : This figure is not to scale. Read the technical note , below, to get a more accurate description. Figure 6. In the case of alternating current AC , the free electrons collectively move back and forth.
Remember, just like in Figure 5, this figure is not to scale. Read the technical note, below, to get a more accurate view. Figure 7. Illustration of how electrons bounce around between atoms in a conductor where the overall drift in one direction creates the electric current. References and Further Reading:. Your email address will not be published. Related Posts. A Life of Discoveries — the great Michael Faraday.
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