Question 1

Light passing from air into empty space will

Accepted Answer

Light travels faster in a vacuum (empty space) than in air, so it will speed up when passing from air into empty space.

Question 2

Light travels at about 300 million meters per second, and it takes light 100,000 years to go from one end of our galaxy to the other. How many miles across is our galaxy?

Accepted Answer

To calculate the distance across the galaxy in miles, first convert the time to seconds (100,000 years * 365.25 days/year * 24 hours/day * 3600 seconds/hour), then multiply by the speed of light (300,000,000 meters/second) to get the distance in meters, and finally convert meters to miles (1 meter = 0.000621371 miles). The correct calculation leads to a distance of about 5.878625 trillion miles, which is approximately 9.461x10^15 kilometers, or in the format given in the options, 9.3x10^21 meters, recognizing the scientific notation and unit conversion.

Question 3

Although sugar looks white, it is clear when placed in water (before dissolving) because

Accepted Answer

Sugar appears clear in water before dissolving because the optical environment outside the crystal becomes closer to that of the crystal itself, which decreases the impedance mismatch, allowing light to pass through with less scattering.

Question 4

You can get a sunburn on your face from sunlight reflecting off snow because

Accepted Answer

Snow reflects up to 80% of UV radiation, increasing exposure and risk of sunburn. This reflection, not added energy or brightness, causes burns. Cold weather does not cause sunburn; UV radiation does.

Question 5

A laser light beam can travel much farther than a flashlight without spreading out because laser light

Accepted Answer

Laser light is coherent, meaning that the waves are all in phase with each other. This allows the light to travel in a straight line without spreading out.

Question 6

Suppose you are hired by a Hollywood firm to create a sunset on a planet just like the earth but where the sunlight was purely monochromatic and red. How should your set look?

Accepted Answer

The answer of Suppose you are hired by a Hollywood...

Question 7

In what way is light from a sodium vapor lamp unlike sunlight?

Accepted Answer

Sunlight is composed of a broad spectrum of colors, whereas light from a sodium vapor lamp is nearly monochromatic, typically emitting a very narrow range of wavelengths centered around the yellow part of the spectrum. This is due to the specific electronic transitions of sodium atoms, which do not produce the broad spectrum seen in sunlight.

Question 8

There is a simple explanation for why bluer "cool white" fluorescent lamps are slightly more energy efficient than redder "warm white"
Lamps. It is because

Accepted Answer

The answer of There is a simple explanation for why...

Question 9

While low pressure sodium vapor lamps are the most energy efficient light sources commonly available, producing a pure orange-yellow light with a wavelength of 590 nanometers, high pressure sodium vapor lamps produce a richer spectrum of light that is more pleasing to the eye. One effect that contributes to this richer spectrum is

Accepted Answer

Radiation trapping occurs when light, such as the 590 nanometer light produced by sodium vapor lamps, has difficulty escaping from the lamp due to repeated absorption and re-emission by the gas atoms. This effect contributes to the richer spectrum of high pressure sodium vapor lamps by allowing more time for the light to interact with the gas and potentially undergo processes that broaden the spectrum.

Question 10

Suppose that you are stranded in a huge office building and are forced to build fluorescent lights without phosphors on the inside.
-If you run the lights with mercury vapor in them what kind of light will the bulbs apply to the office? Please explain.

Accepted Answer

The answer of Suppose that you are stranded in a...

Question 11

Suppose that you are stranded in a huge office building and are forced to build fluorescent lights without phosphors on the inside.
-If you want to replace the mercury vapor with some other vapor that will yield a lot more visible light , should the electron energy levels in the new material be closer together or farther apart? Please explain.

Accepted Answer

The answer of Suppose that you are stranded in a...

Question 12

Using three similarities and three differences please compare and contrast fluorescent light bulbs and incandescent light bulbs.

Accepted Answer

The answer of Using three similarities and three differences please...

Question 13

What colors are the eye's color-sensing cells most sensitive to?

Accepted Answer

The eye's color-sensing cells, known as cones, are most sensitive to red, green, and blue. These primary colors are the basis for the trichromatic theory of color vision.

Question 14

If you have a white light source and are able to subtract blue from it you will be left with

Accepted Answer

When you subtract blue from white light, you are left with yellow. White light is a combination of all colors, and removing blue essentially leaves you with the combination of the remaining primary colors of light, red and green, which mix to produce yellow.

Question 15

The energy of a photon of red (wavelength 6.626x10^-7 m) light is

Accepted Answer

The energy of a photon can be calculated using the equation E = hc/λ, where h is Planck's constant (6.626x10^-34 J·s), c is the speed of light (3x10^8 m/s), and λ is the wavelength of the light. Substituting the given values for red light (λ = 6.626x10^-7 m), the energy E is found to be approximately 3x10^-19 J, making option B correct.

Question 16

Light is emitted when electrons

Accepted Answer

When electrons jump down in energy levels, they release energy in the form of light or photons. This process is fundamental to how atoms emit light.

Question 17

In what way is light from a sodium vapor lamp like sunlight?

Accepted Answer

Both sodium vapor lamps and sunlight involve excited electrons. In sodium vapor lamps, electrons are excited and emit light as they return to lower energy levels, similar to the process in the sun where electrons in atoms are excited and emit light.

Question 18

If you have a white light source and are able to subtract yellow from it you will be left with

Accepted Answer

The answer of If you have a white light source...

Question 19

Putting phosphors inside a sodium lamp is a poor idea because

Accepted Answer

Sodium lamps emit light at a relatively low energy level, primarily in the yellow part of the spectrum. Phosphors require higher energy light, typically in the ultraviolet range, to be excited and emit visible light. Since sodium lamps do not produce sufficient high-energy light, phosphors would not be effectively excited to glow, making it a poor combination.

Question 20

You work for a light company and you want to pleasantly surprise your boss. Would it work if you replaced the mercury vapor in fluorescent lights with something that makes more visible light so the lights would be brighter? Please explain.

Accepted Answer

The answer of You work for a light company and...

Quiz 13: Light