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Answers to Readers' Questions on Physical Science:

Visbile Light

The following 3 comments and questions have been sent in. They are listed according to date.

List of first 10 items

• From where does light get the energy?
• Can light bend?
• Can a laser be used for heating?

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From where does light get the energy?

Question

January 7, 2010

From where does light get the energy to travel so fast and so far. At 186,000m/sec and traveling for billions of years, where does the energy come from that drives the light to us from distant galaxies? That's a lot of energy!

Dr. Jan - USA

18994

Answer

Since a light particle (photon) is so small, it does not take much energy in an atom to accelerate it to 186,000 mi/sec. It is like the reaction to an explosion. When many photons move, they are in the form of light waves.

From Newton's Law of Inertia, once an object starts moving, it will continue unless acted on by a force. Thus, light will travel forever until it strikes some object that will absorb its energy (like light from the Sun heating the planet). So, it doesn't take any more energy to travel for years.

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Can light bend?

Question

August 5, 2008

is it possible to bend light?

dekota - Australia

16313

Answer

Yes, bending light is called refraction.

See: www.school-for-champions.com/science/light_refraction.htm

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Can a laser be used for heating?

Question

November 20, 2006

visible light carries heat or infra red radiations ffrom sun which are coming along with light? if visible light is not producing heating then how laser can?

raghuvir - India

12435

Answer

The sun radiates many wavelengths of the electromagnetic spectrum, including visible light and infrared. On the other hand, a laser only radiates in very specific wavelengths. Red is the most common color or wavelength. But there are lasers that radiate only in the infrared, and they are good for heating objects.

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