electromagnetic force
(noun)
a long-range fundamental force that acts between charged bodies, mediated by the exchange of photons
Examples of electromagnetic force in the following topics:
-
Maxwell's Predictions and Hertz' Confirmation
- Maxwell's prediction of the electromagnetic force was confirmed by Hertz who generated and detected electromagnetic waves.
- Combining the work of physicists including Oersted, Coulomb, Gauss, and Faraday, and adding his own insights, James Clerk Maxwell developed a complete and overarching theory showing electric and magnetic forces are not separate, but different forms of the same thing: the electromagnetic force.
- The strength of the force is related to the electric constant ε0, also known as the permitivity of free space.
- A changing magnetic field induces an electromotive force (emf) and, hence, an electric field.
- Explain how Maxwell's prediction of the electromagnetic force was confirmed by Hertz
-
Nuclear Fission
- The strong nuclear force is the force between two or more nucleons.
- The electromagnetic force causes the repulsion between like-charged protons.
- The strong nuclear force acts to hold all the protons and neutrons close together, while the electromagnetic force acts to push protons further apart.
- In atoms with small nuclei, the strong nuclear force overpowers the electromagnetic force.
- As the nucleus gets bigger, the electromagnetic force becomes greater than the strong nuclear force.
-
Applications of Newton's Laws
- Net force affects the motion, postion and/or shape of objects (some important and commonly used forces are friction, drag and deformation).
- Friction is not itself a fundamental force, but arises from fundamental electromagnetic forces between the charged particles constituting the two contacting surfaces.
- Another interesting force in everyday life is the force of drag on an object when it is moving in a fluid (either gas or liquid).
- Like friction, the force of drag is a force that resists motion.
- We see an illustrated example of drag force in.
-
Constant Velocity Produces a Straight-Line
- There are many cases where a particle may experience no net force.
- The particle could exist in a vacuum far away from any massive bodies (that exert gravitational forces) and electromagnetic fields.
- Or there could be two or more forces on the particle that are balanced such that the net force is zero.
- Recall that the magnetic force is:
- In the case above the magnetic force is zero because the velocity is parallel to the magnetic field lines.
-
The Production of Electromagnetic Waves
- Electromagnetic waves are the combination of electric and magnetic field waves produced by moving charges.
- Electromagnetic radiation, is a form of energy emitted by moving charged particles.
- The creation of all electromagnetic waves begins with a charged particle.
- This charged particle creates an electric field (which can exert a force on other nearby charged particles).
- These and many more such devices use electromagnetic waves to transmit data and signals.
-
Superposition of Forces
- The superposition principle (superposition property) states that for all linear forces the total force is a vector sum of individual forces.
- Therefore, the principle suggests that total force is a vector sum of individual forces.
- Of course, our discussion of superposition of forces applies to any types (or combinations) of forces.
- Total force, affecting the motion of the charge, will be the vector sum of the two forces.
- (In this particular example of the moving charge, the force due to the presence of electromagnetic field is collectively called Lorentz force (see ).
-
Electric Motors
- If you were to place a moving charged particle in a magnetic field, it would experience a force called the Lorentz force:
- Your third finger will now be pointing in the direction of the force.
- This results in a changing flux, which induces an electromagnetic field.
- Any coil carrying current can feel a force in a magnetic field.
- This force is the Lorentz force on the moving charges in the conductor.
-
Energy Transportation
- In this sense the wave has done work (it applied a force over a distance).
- Similarly we find that electromagnetic waves carry energy.
- Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields .
- The photon is the quantum of the electromagnetic interaction, and is the basic "unit" or constituent of all forms of EMR.
- Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields.
-
Magnitude of the Magnetic Force
- Magnetic fields exert forces on moving charges, and so they exert forces on other magnets, all of which have moving charges.
- The magnetic force is as important as the electrostatic or Coulomb force.
- The strongest permanent magnets have fields near 2 T; superconducting electromagnets may attain 10 T or more.
- Magnetic fields exert forces on moving charges.
- This force is one of the most basic known.
-
Electromagnetic Spectrum
- The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation.
- The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation.
- The electromagnetic spectrum of an object has a different meaning: it is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.
- Whenever electromagnetic waves exist in a medium with matter, their wavelength is decreased.
- The behavior of electromagnetic radiation depends on its wavelength.