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If light is electromagnetic then can light produce electricity or attract metals?

Physics Asked by Saranya Nayak on June 24, 2021

what I mean to say is that if light is electromagnetic in nature then shouldn’t it show electric or magnetic properties on matters? Like if light falls on a metal it should produce current due to its electric nature but it doesn’t. Secondly due to its magnetic nature shouldn’t it attract metal object or get deflected t words then or magnetite them due to its magnetic field?

5 Answers

Of course, light can produce electricity. It is called Photoelectric effect. When photons with sufficient energy strike a metal plate, electrons are emitted. Einstein got his Nobel for successfully explaining the photo-electric effect. Other examples are light sensitive diodes, solar energy cells. As a matter of fact, we see things when light falls on our retina in the eye, tiny electrical signals are produced and they are carried to our brain through optic nerve. That is how we see things.

Answered by Subodh G. Gokhale on June 24, 2021

Light is electromagnetic in nature

Yes of course light is electromagnetic in nature, but one thing you have to understand that light is made up of photons. And "photons are packets of energy" and are not matters like electrons and protons.

Light is electromagnetic in nature then shouldn't it show electric or magnetic properties on matters

It turns out that the photons which make up a static electric or magnetic field are "virtual" -- their energy and momentum doesn’t satisfy the relationship for "real" photons -- E=p*c (E is energy, p=momentum, and c is the speed of light). The virtual photons are constantly emitted and reabsorbed. A charged object with an electric (and possibly also a magnetic) field is surrounded by an entourage of photons, constantly being emitted and reabsorbed.

Photons, real and virtual, are emitted and absorbed by charged particles, even though they are not charged themselves. They only interact with charged particles, and not with each other. That’s why photons don’t interact with magnetic fields -- the photons which make up the magnetic field are not charged so other photons cannot interact with them.

Photoelectric effect of light is due to the fact that photons can be absorbed by electrons and not merely because it has electric field.

Source - Grahame

Answered by Kawin M on June 24, 2021

Other people wrote about photoelectric effect. Light can also cause mechanical motion of both metals and non-metals ( radiation pressure - https://en.wikipedia.org/wiki/Radiation_pressure )

Answered by akhmeteli on June 24, 2021

I think the OP is refering to the classical nature of light (not the famous quantum effects associated to it). Like, EM radiation can stimulate antennas or induce electric currents on conductors - if light is EM radiation then why doesn't it create electrial currents on conductors?

This is because the wavelengths are so small (light is in the THz range) that making antennas for it becomes very very challenging, as the antenna size is inversely proportional to the wavelength. Also the plasma frequency of most conductors is smaller than the frequency of visible light, so the electrons just bounce back and forth quickly with no detectable EMF - this is not the case for lower frequency signals (let's say, radio or TV signals) so the radiation can indeed cause a EMF on the conductor.

Answered by strange_bakery on June 24, 2021

An example of a charged, magnetic particle that can be manipulated by light is the electron. With light it can be excited into a higher atomic or molecular orbital. When it falls back it emits light. Light or better the closely related microwaves can flip its magnetic moment in EPR.

Answered by my2cts on June 24, 2021

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