-1
$\begingroup$

Could anyone tell at high level without being so too much tech details what is the difference between Electromagnetic wave and Electric current?

On lighter node, if i touch the wire carrying current we get shock, is it the same for electromagnetic wave too?

$\endgroup$
  • 1
    $\begingroup$ Billions of electromagnetic waves are hitting you at the moment. Your screen is emitting these waves and these waves are entering your eyes. When these hit your eye's retina, it creates an electrical impulse in your eye nerves. This is how you see things. $\endgroup$ – Yashas Feb 25 '17 at 13:21
  • $\begingroup$ Have you tried studying basic electrodynamics? $\endgroup$ – Peaceful Feb 25 '17 at 13:44
1
$\begingroup$

Electric current is the movement of electric charge through a conductor. For example, an electric charge carried by electrons through a wire.

An electromagnetic wave does not require a conductor. Electromagnetic waves are created by moving electric charges, but once created, they can propagate through a vacuum. Photons are the smallest packets of energy that propagate as electromagnetic waves.

In a vacuum, photons travel without being absorbed and re-emitted by a medium. But if an electromagnetic wave propagates through a medium, photons excite atoms, and this excitation is passed from atom to atom through the medium. The absorption and re-emission of photons slows the wave as it passes through the medium. Therefore the speed of an electromagnetic wave propagating through vacuum is greater than any propagation through a medium.

You can "feel" an electromagnetic wave if it excites the atoms in your body and causes them to vibrate as they absorb and re-emit photons, giving off heat. For example, sunburn is caused by photons from the Sun.

Electromagnetic waves should be distinguished from electromagnetic fields, which exert force upon electric charges in the vicinity. When an electromagnetic field oscillates, it manifests as the propagation of an electromagnetic wave. When it is static, it manifests only by its effect upon an electric charge.

There has been a great deal of controversy about the effects of electromagnetic fields upon humans. Electromagnetic hypersensitivity to electromagnetic fields has been reported, but no scientific basis for these reports has been found.

$\endgroup$
  • $\begingroup$ Thanks Ernie. One Thing is clear that EW does not require medium but EC does. But you said Electric current is the movement of electric charge through a conductor. For EW you said Electromagnetic waves are created by moving electric charges. Does it mean both are created by movement of electric charges wheres as electric charge is electrons in case of EC while electeric charge is photon in case of EW? $\endgroup$ – scott miles Feb 26 '17 at 0:39
  • $\begingroup$ @scottmiles : Electrons carry negative charge, whereas photons commonly carry positive charge. Electric current commonly is caused by electric potential difference across a circuit. Electromagnetic waves, however, are caused by accelerating (oscillating) electric charges. Current requires a conductor or medium. Electromagnetic waves don't require a conductor or medium. Electric current is charge in motion. Electromagnetic waves are caused by charge in motion, and can propagate from a current-carrying conductor. $\endgroup$ – Ernie Feb 26 '17 at 2:18
  • $\begingroup$ "Electromagnetic waves are created by moving electric charges..." "photons commonly carry positive charge." Those are both false. $\endgroup$ – Quantumness Jun 23 at 19:17
1
$\begingroup$

Ernie's answer ain't bad at all, but then his later comment has a few problems. He states EWs are created by moving electric charges; actually, they are created by accelerating charges which engender changing electric fields, or changing magnetic fields. All the behavior of electromagnetics, static and dynamic, is encapsulated in Maxwell's equations. Electric current can be comprised of moving negative or positive charges, and a constant current produces a constant magnetic field. Electrons indeed carry negative charge, but photons, the gluon for the electromagnetic force that propagates through space, does not have a charge. It can be described as a self-regenerating, propagating wave composed of changing magnetic and electric fields. It carries no charge, but does carry energy, momentum, and spin.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.