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by Ron Kurtus

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

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List of next 10 letters




Dispersion of Light Why is rainbow always circular in shape? India
X-rays Wants detailed information on x-ray science Uganda
Speed of Light Where is the speed of light highest? India
Laser Game I say light has no momentum RZA
Dispersion of Light Why doesn't a glass of water show a rainbow? India
Dispersion of Light Why is the dispersion of a slab equal to zero? India
Dispersion of Light What is the role of green light with plants? USA
X-rays Can x-rays detect harmful or heavy metal in water? India
X-rays Can we use alpha or beta particles to make a new metal? India
EM Waves Does the human body emit electromagnetic waves? India

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First 10 letters

Why is rainbow always circular in shape?

Topic: Dispersion of Light


October 9, 2010

Why is rainbow always circular in shape?

Pullarao - India



You will find the sun is always behind you when you see a rainbow. A line from the center of curved shape of the rainbow will go directly to the sun.

The water droplets creating the rainbow reflect the light toward you at a different angle, thus the circular shape.

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Wants detailed information on x-ray science

Topic: X-rays


September 27, 2010

thanks for the important information you normally give us, but i have a few questions with me here.
1. state for me some few examples of x-ray tubes comonly used in both the medical and industrial purposes.
2.what are the basic parts of an x-ray machine that is used in the medical field and their basic functions.
3.what are the different imaging modalities in the medical field that uses x-rays.
4. and how do the x ray machines for the different modalities differ especially in the accessory apparatus
5.what is the minmum amount of energy that is carried by an x ray.
6.what is an x ray and what is made of?{the basic design of x ray film}.
7.describe the characteristics of matter and energy.
8.what is ionizing radiation and state its sources both natural and artificial sources.
9.what are the effects of ionizing radiation on both the environment and huumans.

ATEGEKA - Uganda



I am sorry, but we do not have such detailed information. Some websites you can check into for answers are:

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Where is the speed of light highest?

Topic: Speed of Light


September 14, 2010

speed of light is maximum in water, air or steel?

Draj - India



The speed of light is usually given in a vacuum. It is a little slower in air and much slower in water. Light does not usually travel through steel.

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I say light has no momentum

Topic: Laser Game


September 5, 2010

Your quiz at the "Laser Battle Game" is faulty. There should be NO RECOIL, as photons have no mass, and thus no momentum. P = MV (P being momentum, M mass and V velocity). if M = 0 P will also = 0




There are several space vehicles that are using a solar sail to help them move to their destination. The light from the Sun applies pressure on the sail, as a function of the momentum of the light beam.

It is true that photons have no resting mass, however the standard equation for momentum, p = mv, does not hold with electromagnetic waves. Instead, the equation p = hf/c is used, where h is the Planck constant, f is the frequency of the light and c is the speed of light.

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Why doesn't a glass of water show a rainbow?

Topic: Dispersion of Light


August 29, 2010

Why do we not see a rainbow if we shine light on a glass of water? Does dispersion not happen then?

Pankaj - India



If you shine a light from a point source for very small stores through a glass of water, you will see a slight rainbow at the edges of the image.

The way a rainbow works is that there are many small droplets of water that caused the dispersion of the light into its spectrum. The light reflex inside the droplet and returns in the opposite direction.

When you face a rainbow, the water droplets are in the sky in front of you and the Sun is always at your back.

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Why is the dispersion of a slab equal to zero?

Topic: Dispersion of Light


July 26, 2010

ifdispersive power is property of the material why dispersive power of the slab comes to be 0.

pramod - India



Dispersion is a property of the material, but the amount also varies with the angle difference of the incoming and outgoing light. In a parallel slab of material, the angle difference is zero, so there is no dispersion.

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What is the role of green light with plants?

Topic: Dispersion of Light


July 21, 2010

Plants are green (±); the strongest light color penetrating to the terresphere is green. Does this mean plants are mitigating the impact of the strongest light, so as not to "burn" in sunlight? Or what?

Dusty - USA



The green color you see on plants is from light that is reflected. The chlorophyll in plants primarily absorbs light blue and red portions of the light reaching them. However, it is a poor absorber of green and near-green portions of the spectrum.

If the greatest intensity of light penetrating to the plants is green, reflecting that color may protect them from harm in sunlight.

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Can x-rays detect harmful or heavy metal in water?

Topic: X-rays


July 4, 2010

can we use x-ray to detect harmful/heavy metel in water?

sandeep - India



Harmful or heavy metal in water is usually in the form of a solution or extremely small particles that can not be distinguished with x-rays. There are simple chemical tests that can find out about the materials in the water. If you have an idea what specific metal may be in the water, such as lead, you can check it by filtering a sample solution with a filter made of compressed cerium phosphate fibers to see if the paper discolors.

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Can we use alpha or beta particles to make a new metal?

Topic: X-rays


June 28, 2010

can we use alfa/beta/gama decay to make new matel with there own properties

sandeep - India



Unstable metals could decay alpha or beta particles, resulting in a different element that has different properties than the original metal. Gamma rays might also be released in the decay.

You could also bombard a battle with alpha or beta particles that might also cause some changes.

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Does the human body emit electromagnetic waves?

Topic: EM Waves


June 15, 2010

This is really helpful! I have a question; does human body emit electromagnetic waves?

srishtee - India



The nerves in the body work through electrical impulses, that in turn give off very weak electromagnetic waves of long wavelengths. There are devices that measure the human heart and brain waves that pick up those waves.

Also, the warmth of the body gives off infrared radiation, which are also electromagnetic waves.

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