Bi-focals! Glasses with +0 on top and +3 on bottom
What color of visible light has the lowest frequency?
Which color of visible light has the highest frequency?
What is the fate of UV light that is cast on to glass?
It will not go through.
What happens to visible light that is incident upon glass?
It passes through easily.
Do Earth and Moon always cast shadows?
Located on edge of eye see black and white Detect motion Used in dark
Located in fovea (center) see color Detect fine print Need bright lights
What has the longest wavelength?
Which has the shortest wavelength? UV or IR?
Which has a higher frequency? UV or IR?
Is the speed of light independent of frequency?
Yes, all light travels at the same speed.
You can get sunburn on a cloudy day, but you can't get sunburn on a sunny day if you are behind glass. Explain
UV in blocked by glass but not by clouds
Suppose that sunlight falls both on a pair of reading glasses on a pair of dark sunglasses. Which pair of glasses would you expect to become warmer?
Dark absorbs light and gets warmer
Why does a high-flying airplane cast little or no shadow on the ground below while a low-flying airplane casts a sharp shadow?
Low flying plane the umbra reaches the ground, high plane umbra doesn't.
Why do object illuminated by moonlight lack color?
In the dark you use your rods and rods only see black and white
Why do we not see color at the periphery of our vision?
Rods are peripheral and rods cannot see black and white
In which medium does light travel faster, in thin air or in dense air? What does this difference in speed have to do with the length of a day?
Light travels faster in thin air, making the day 6 minutes longer
Is a mirage the result of reflection or refraction?
Refraction, mirage caused by hot and thin air on the road allowing light to move faster and bend.
Does a single raindrop illuminated by sunlight deflect light of a single color or does it disperse a spectrum of colors?
Does a viewer see a single color or a spectrum of colors coming from a single faraway drop?
Which kind of road surface is easier to see when driving at night- a pebbled, uneven surface or a mirror-smooth surface?
Rocky road because it reflects more light back to the eye.
And why is it difficult to see the roadway in front of you when driving on a rainy night?
Rainy night- water reflects light and diffuses reflection
What is the minimum length of a plane mirror in order for you to see a full image of yourself?
Half of your height
If while standing on a bank you wish to spear a fish beneath the water surface in front of you, should you aim above, below or directly at the observed fish to make a direct hit?
-Below because of refraction the speed of light is slower in water.
If instead you zap the fish with a laser, should you aim above below or directly at the observed fish?
-Directly at it, the water will bend the light aiming it at the fish because of refraction
If the fish in the previous question were small and blue and your laser light were red, what corrections should you make?
Blue light bends more; the laser would miss, thus you need to aim below the fish.
A rainbow viewed from an airplane may form a complete circle. Where will the shadow of the airplane appear? Explain.
Right at the center of the rainbow. The point of the plane is the anti-sun.
Suppose you walk toward a mirror at 2 m/s. How fast do you and your image approach each other?
4 m/s, as both of you are travelling at 2 m/s.
A butterfly at eye level is 20 cm in front of a plane mirror. You are behind the butterfly, 50 cm from the mirror. How far away are you from the butterfly in the virtual image?
50cm from you to mirror, 20cm from mirror to virtual butterfly. Thus, 70cm.
Electromagnetic spectrum from shortest wavelength to longest:
Gamma rays x-rays Ultraviolet rays Blue Green Red Infrared Microwave Radio
Electromagnetic waves with wavelengths of 300 meters are called:
AM radio waves
The constantly moving bright and dark areas at the bottom of a swimming pool are caused by:
Electromagnetic waves with wavelength of 7000 angstroms are:
Red and visible to your eye
What has the lowest frequency?
The moonbow looks grey or silvery to most people, and objects seen by moonlight usually are not colored because moonlight:
Is too dim to activate the eye's cones, so rods are used
Correct property of the eye's cones?
Concentrated near center of eye and detect color
Correct property of the eye's rods?
Found mainly around periphery of vision and used to detect motion
If a total solar eclipse occurs, then we know that
The umbra of the moon is touching the earth. (Sun>Earth>Moon)
What must be the phase of the moon on the day of a lunar eclipse?
Phase of the moon during a solar eclipse?
Who can see a total lunar eclipse?
Anyone on the half of the Earth toward the moon
Red/Orange in color and can be seen during a total solar eclipse
What is the minimum size of a plane (flat) mirror, so that children who are four feet tall can see their full height in the mirror?
2 feet tall
Atmospheric refraction makes the daylight hours
Longer than they would be otherwise
A hot road mirage is caused by
If you stand next to a swimming pool and lok down into the water, the image that you see of the fish swimming in the pool appears to your eye to be:
shallower than the actual fish
A primary rainbow is brighter than a secondary rainbow because:
Loos of light when the secondary has an extra reflection inside the drops
In a rainbow display, one of the places where we see a diffuse white glow is:
Next to the blue/violet bands of the primary bow
In a rainbow display, what colors do we see immediately next to Alexander's dark band?
Red on both sides from both rainbows
In making the secondary rainbow, each light ray does what in passing through a raindrop?
2 reflections, 2 refractions
When seen from an airplane, a rainbow can form a complete circle. The plane's shadow is:
In the center of the rainbow
If you see the primary rainbow in the sky, the sun must be:
Within 42 degrees of the horizon
If you view a rainbow just before the sun sets in the west, then you must be looking generally:
Examples of thins that are caused because light can refract (bend)
-mirages -rainbows -flattening of the sun
If you were to spear a fish by throwing a regular (metal) spear, you should aim:
Below the observed fish
If you wish to illuminate a red fish with a blue laser beam, you should aim your laser beam where?
Slightly above the observed fish
When passing from air through a glass prism and back out into air...:
Blue bends more than red, since blue travels slower than red does in glass
As you look at a setting sun, where would you point to show the direction of the actual sun?
About one solar diameter below the visible sun
The desert mirage, or hot road mirage, is related to?
A layer of cooler air over a layer of hotter air, and that light travels slower in cooler air
When a ray of light passes from water out into the air, the ray is bent
Away from the normal
If all colors slowed down in glass, but all colors traveled at the same speed in glass, then a beam of white light would strike a prism, pass through, and emerge on the far side as:
Bent, but not spread into colors
When you watch a movie at a theater, the image on the screen is, technically,:
An upside down image of the film frame
A scuba diver shines a light beam up towards the surface of a smooth pond at a 10 degree angle to the normal. Some light passes into the air above, and the part that reflects back into the water makes an angle to the normal of:
What color does the moon often appear, during a total lunar eclipse?
If you want to use a converging lens of 4 cm focal length as a magnifying glass to look at the fine details on a coin, you should put the coin where?
3.9 cm from the lens, to obtain a virtual enlarged image
A lens with a power of +7 diopters has a focal length of
For myopia, the eye doctor prescribes:
Hypermetropia (hyperopia) is also know as
If you try to read a book, but the image forms behind your retina (outside your eyeball), then you need converging glasses (positive power) and your problem is called:
A butterfly at eye level is 30 cm in front of a plane mirror. You are behind the butterfly, 50 cm from the mirror. What is the distance between your eye and the butterfly's image in the mirror?
My movie projector has a lens with 200 mm focal length. When projecting "E.T." in a large room, each film frame should pass about how far from the center of the lens?
When you look through a diverging lens, you always see a
Virtual image, right-side up
In which substance does light move the slowest?
If a red light signal and a radio signal were emitted simultaneously from a distant star system, which would reach our solar system first?
Both would reach us at the same time
A lens with a positive power (for example +2 diopters) must be a:
Converging lens (one that brings parallel rays of light together to a focus)
Which one of these parts of the electromagnetic spectrum has the highest frequency?
The shadow that is totally dark and tapers down to a point is called the:
If a fish looks upward at 45 degrees with respect to the normal of the water's surface, it sees:
Clouds in the sky
If you are standing 6 feet away from a flat mirror, what is the distance between you and your image in the mirror?
The people that see a partial solar eclipse are the people that observe from the:
It is difficult to see the road ahead of your car on a rainy night because wet roads have:
More mirror-like reflection, which bounces your headlight beam away from you