Electric and Magnetic Fields

A field is a mathematical role that assigns a amount to each point in space. Scalar fields assign scalar quantities to each allude in space; vector areas assign vectors to each suggest in space. In physics, vector areas are provided to represent the behaviors of forces. For example, the actions of gravitational forces can be stood for by assigning vectors come points in space, wherein each vector represents the magnitude and direction that the gravitational force that would be exerted on things located at the point.

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Electric and magnetic pressures can also be stood for by vector fields. Every charged thing is surrounding by an electric field. The strength and also direction that the electric field in ~ each suggest is identified as the pressure that would be exerted top top a particle with 1 coulomb of positive charge if the bit were situated at that suggest (whether or no such a bit is actually situated there).

Simulation the an electric Field

Drag a couple of positive and/or an unfavorable charges (red and also blue circles) into the space. Then add electric field sensors (yellow circles) to watch the force vectors at any type of given point. Also shot checking the “Electric Field” crate to visualize the electric field lines.


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Images by Geek3, an innovative Commons patent CC BY-SA 3.0. Click photos for initial files. These files have no been modified.

The actions of pressures can additionally be usefully represented using ar lines. Field lines room the present (or curves) through room that follow the direction of the force vectors at each point. In various other words, they room the paths that would be traced by objects that move in small increments, adhering to the direction of the pressure vector in ~ one suggest to a nearby point (without going the complete length that the vector), then complying with the direction of the second point’s vector for a short distance to a 3rd point, and so on. Ar lines do not display the magnitude (strength) the the forces at each point, however they make it straightforward to visualize just how the directions of the vectors readjust over a an ar of space.

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When an electric present flows follow me a straight wire, magnetic ar lines kind concentric circles around the wire.

A magnetic field is an additional kind of vector field linked with electrical charges. The direction of the magnetic force vectors at each allude correspond come the direction in i m sorry the phibìc pole that a magnet would be moved if that were situated at the point. Magnetic areas are developed whenever a charged thing moves. When a charged object move in a straight line, the magnetic field lines type concentric one perpendicular to the object’s direction the travel. For example, once an electric current moves follow me a directly wire, magnetic field lines type circles roughly the wire. (An electric present is a circulation of charged particles, normally electrons.)


Physicists stand for the direction of an electric current as opposite the direction that electron flow. Because that example, if the electron are relocating to the right, the electric existing is pertained to as flowing to the left.
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When an electric present travels roughly a wire loop, magnetic field lines flow through the loop in one direction. The outflowing next is a magnetic north pole; the inflowing next is a south pole.

Now imagine what wake up if we take that wire and bend it into a loop so that the current moves in a circle. Magnetic ar lines pass with the loop together they encircle every segment of the wire. Every one of these magnetic ar lines circulation through the loop in the very same direction. The result of this plan is a magnetic field with two magnetic poles: the outflowing side of the loop is dubbed the phibìc pole, and also the inflowing next is called the southern pole.

Something comparable happens in ~ the microscope level, as electrons orbit the nucleus of one atom. As each electron spins about the nucleus, that produces a (very weak) magnetic ar with north and south poles. In part atoms, the electron spin in opposite directions, so their magnetic areas cancel each other out. However, the magnetic fields developed by an atom’s spinning electron don’t always cancel out, and also many atoms execute act as miniature magnets. If sufficient of this atoms space aligned in the exact same direction, your magnetic areas work together to develop a much stronger magnetic ar that can be felt at the macroscopic scale. Magnets space simply materials that have actually their atom aligned in this way.

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Magnetic field lines roughly a bar magnetNotice the close same to the electric field lines surrounding a positive and negative charge.
Image by Geek3,Creative Commons patent CC BY-SA 3.0. Click image for original file. This record has no been modified.

Some minerals, prefer magnetite, have actually their atoms naturally aligned. Magnets can additionally be artificially created by placing details metals (e.g. Iron) into a magnetic field, resulting in the atoms to align (temporarily or permanently, depending upon the process) v that magnetic field. For example, a simple temporary magnet have the right to be do by pack wire around a nail, then to run an electric current through the wire. The circling electric charges in the wire produce a weak magnetic field, and the iron atoms in the pond align v that ar so that their very own magnetic areas work with each other to create a much stronger field. Short-term magnets like this are called electromagnets. Products that have actually their atom permanently set are called permanent magnets.

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If you rest a long-term magnet in half, each fifty percent will have actually its own north and south poles. Repeat this procedure as regularly as you like; you’ll never acquire a north pole or a southern pole by itself. Since each atom has both a north and also a southern magnetic pole, it is difficult to obtain a phibìc or south pole alone. In other words, magnetic “monopoles” don’t exist in nature. And also you can’t develop a magnetic monopole in the activities either. Magnetic monopoles just don’t exist.