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Feedback Comments on Electromagnetic Waves

by Ron Kurtus

A total of 311 comments and questions have been sent in. They are listed according to date.

You can read them to further your understanding of the subject.

List of next 10 letters




Infrared Radiation Confused about infrared and heat USA
EM Waves How do the waves travel through space? India
Visbile Light Why are N and Ar gases used in lightbulbs? Bangladesh
EM Waves Are heat waves the same as light waves? Bangladesh
EM Waves Do all materials emit electromagnetic waves? Bangladesh
EM Waves Why do heated materials emit electromagnetic waves? Bangladesh
X-rays Canx-rays see inside a can of vegetables? USA
Visible Light Problem with interference fringes Egypt
EM Waves Creation of the universe and unification theory USA
Visible Light Why does light and heat go hand-in-hand? USA

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First 10 letters

Confused about infrared and heat

Topic: Infrared Radiation


February 3, 2011

The answer on infrared still left me confused. I think most explanations about light and heat are ambiguous. Am I correct to assume that infrared is light but not heat? Heat is heat, it is radiated as a wave and has a wavelength spectrum, just as light as a wave has a spectrum. Infrared is light that radiates simultaneously as heat waves begin. A graphic picture of infrared spectrum would thus not be the same as a graphic picture of the corresponding heat waves, since heat has a longer wavelength than infrared light waves. As light, infrared could cause matter to oscillate, thereby inducing it to radiate heat. Am I correct?

Vince - USA



Infrared radiation is a form of light or electromagnetic radiation. A major property of it is that will increase the energy of molecules and thus heat up an object through its radiation.

Heat then transfers to other objects, such as your skin, by physical contact, convection in heated air or by re-radiating infrared.

Heat is caused by the movement of molecules. A "heat wave" would actually be a wave of heated air that you feel.

A big part of the confusion comes from expressions such as "a heat lamp", which really is an IR lamp that can heat things up and not a lamp that radiates heat.

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How do the waves travel through space?

Topic: EM Waves


January 26, 2011

why electromagnetic waves do not require any material medium for propogation?

Seema - India



Electromagnetic waves consist of changing electrical and magnetic fields. Both travel through space with no material to carry them.

There are a number of theories how electromagnetic waves travel. Many years ago, it was thought that they traveled in a material called aether, but that idea has been dropped. The latest is the the waves travel through series of photon particles.

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Why are N and Ar gases used in lightbulbs?

Topic: Visbile Light


January 26, 2011

Why N and Ar gases are used in normal bulbs?

Tanmay rahman - Bangladesh



Originally, the inside of a light bulb was a vacuum. This is so that the heated filament did not burn up, as it would if it was in contact with Oxygen. However, the bulbs broke too easily. So they put in other gases, such as Argon, that do not react with the Tungsten filament.

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Are heat waves the same as light waves?

Topic: EM Waves


January 25, 2011

1.are visible light waves included in heat waves?what EM waves are c
alled heat waves? there any equation between wavelength and frequency?as like-10^14nm=3000Hz

Tanmay rahman - Bangladesh



What is often called "heat waves" is usually infrared radiation, which has a slightly longer wavelength than visible light.

The speed of light equals wavelength times frequency (c = Lf).

Thus: 3*10^8 m/s = (10^5 m)*(3000 Hz)

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Do all materials emit electromagnetic waves?

Topic: EM Waves


January 24, 2011 every material of the earth emitting EM waves as every material has a temperature itself?Or,is there any limit of temperature when a material will emit certain wavelenth's EM waves?

md.Tanzil - Bangladesh



Most materials do not emit electromagnetic waves unless they are warm or hot. It takes a certain amount of energy for a material to emit the waves. Metals and other materials will often emit infrared radiation at room temperature.

But also realize there are other methods of emitting electromagnetic waves, such as the vibration electrical currents that create radio and television waves.

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Why do heated materials emit electromagnetic waves?

Topic: EM Waves


January 23, 2011

why heated materials emit electromagnetic waves? is the sun only source of electromagnetic waves? What contributes making these waves in the sun?

Tanmay rahman - Bangladesh



Heating a material is one way to create electromagnetic waves--primarily visible light waves. The atoms move faster when heated, and collisions cause electrons to jump orbits and let off light.

Light bulbs, radio transmitters, microwave ovens and x-ray machines are other sources of electromagnetic waves, besides the Sun.

The Sun gives off light because it is hot.

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Canx-rays see inside a can of vegetables?

Topic: X-rays


December 12, 2010

I know that xrays can detect crackes in metal.

Can xrays be used to determine what is inside a can of vegetables?

Thank you.

James Crowe

James - USA



Although strong x-rays can pass through a metal can, the metal will mask anything inside of the can that is less dense. A piece of steel or lead might show up on an x-ray that passed through the metal can, but something soft like vegetables would not be detected.

There are other methods to find out what is inside of the can.

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Problem with interference fringes

Topic: Visible Light


December 11, 2010

a double-slit arrangement produces bright interference fringes for sodium light(waves length=589 nm)that are a regularly separated by 0.30 degree near the pattern center. what is the angular fringe separation if the entire arrangement is immersed in water,which has an index of refraction of 1.33?

ahmed - Egypt



I'm sorry, but working out that problem is beyond the scope of our material.

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Creation of the universe and unification theory

Topic: EM Waves


November 23, 2010

Question - Would you agree!

In accordance with my theory on the “ creation of the universe and unification theory “, I mention the creation of electromagnetic spectrum as carrying gravity, base matter and energy far beyond the current location of the furthermost galaxies.

Sense this action has been taking place for a very long time, the gravitation pull from the accumulated mass on the outside of the galactic positions is great enough to cause their outward acceleration from the point of “ inconsistency “ or center of our formation.

Creation of the Universe & Unification Theory

Thank you,

Robert - USA



I know that there have been several theories concerning the relationship between electromagnetic waves and gravitation. One area in relativity concerned effects from what they call gravitomagnetic force.

Your theory certainly is an interesting approach to the subject. Keep up with the creative thoughts.

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Why does light and heat go hand-in-hand?

Topic: Visible Light


October 19, 2010

Hello! Just wondering... WHY does light go hand in hand with heat? I know that in light bulbs, the resistance between the metal and the electrons in the electric current creates friction releasing energy in the form of heat. But sun can feel hot on your skin even though it doesn't appear to have any mass at all (and therefore not be able to create friction). Why is this? Is there another reason that the suns rays are hot besides friction? Or can light create friction even thought it has no mass?
Thank you!

Kirra - USA



Heat is the movement of atoms and molecules in a material. Once they are moving fast enough, they start to give off extra energy in the form of infrared and visible light. In a light bulb, the resistance to the motion of the electrons causes the atoms to speed up and then give off light.

In the other direction, when light hits an object, must of it is absorbed, which gives the atoms and molecules extra energy and thus heats them up. Infrared radiation creates more heat than visible. Dark colors absorb more infrared and visible light and thus get warmer faster than do light colors or shiny objects.

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