electromagnetic force

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

• 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.

• Solenoids, Current Loops, and Electromagnets

  • Solenoids are important because they can create controlled magnetic fields and can be used as electromagnets.
  • Electromagnetism is the use of electric current to make magnets.
  • These temporarily induced magnets are called electromagnets.
  • Combining a ferromagnet with an electromagnet can produce particularly strong magnetic effects.
  • An electromagnet creates magnetism with an electric current.

• Sources of EMF

  • Electromotive force (EMF) is the voltage voltage generated by a battery or by the magnetic force according to Faraday's Law of Induction.
  • Electromotive force, also called EMF (denoted and measured in volts) refers to voltage generated by a battery or by the magnetic force according to Faraday's Law of Induction, which states that a time varying magnetic field will induce an electric current.
  • Electromotive "force" is not considered a force (as force is measured in newtons) but a potential, or energy per unit of charge, measured in volts.
  • In the case of an electrical generator, a time-varying magnetic field inside the generator creates an electric field via electromagnetic induction, which in turn creates an energy difference between generator terminals.
  • Give examples of the devices that can provide the electromotive force