Intro to Visible Light

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Question 1: Is purple light related to radio waves?

• No

• Yes

Answer explanation

Yes. All visible light (any color) and radio waves are part of the electromagnetic spectrum.

Can a welding arc emit ultraviolet (ultraviolet causes sunburns and skin cancer)?

• No

• Yes

Answer explanation

Yes. A welding arc can give burns like sunburns because it emits ultraviolet.

If we see no rays of light, does that always mean there’re no rays?

• No

• Yes

Answer explanation

No. If they’re are pointing away from us and not hitting something, we won’t see them.

Can a gray, rough rock (that is not shiny) reflect light?

• No

• Yes

Answer explanation

Yes. That's why we are able to see gray, rough rocks.

Does refraction explain why a spoon's handle seems bent in water?

• No

• Yes

Answer explanation

Yes. Light bends when going from air into water (& vice versa) in a process called refraction.

Do rainbows make the colors red, green and blue?

• No

• Yes

Answer explanation

No. White light that enters water droplets already contains light colors that are red, green and blue (among others). The water droplets just separate the colors.

Does light from lightbulbs contain energy that we can capture?

• No

• Yes

Answer explanation

Yes. Solar cells on our devices (e.g., calculators) capture some of that energy in light.

When outside in the sunlight, is white paper hotter than black paper?

• No

• Yes

Answer explanation

No. Black paper is hotter. Dark inks and paints absorb more light energy than less dark ones, then turn that light energy into heat energy.