Name: Date:

𝑑 𝑣= 𝑡 𝑣 = 𝜆𝑓

Period:

Light GUESS & Practice

Since light has the same speed in the same material it travels at a constant speed until it enters a new material. The speed of light in air is very close to the speed of light in a vacuum so we can use 3x108m/s for the speed of light in air. All waves have an inverse relationship between wavelength and frequency. The ________ the frequency the smaller the wavelength and the lower the frequency the _________ the wavelength.

1. The Earth is about 40,075,000 m around (circumference). If light travels at 3x108m/s or (300,000,000 m/s) how long will it take light to go around the Earth once? G U E S S

2. How far does light travel in one second? G U E

S

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3. Take your answer from above and divide it by 40,075,000 m around (the circumference of the Earth). This is how many times light can travel around the Earth in one second.

4. Sound travels an average of 343 m/s. How long does it take for sound to travel 1 km (or ______ m)? G U E S S

5. How far does light travel at 300,000,000 m/s in the time you got for the last problem? G U E S S

6. According to your notes red light has a wavelength of _____ nm which means 0.0000007 meters. What is the frequency of red light if light travels at 300,000,000 m/s? G U E S S

7. According to your notes violet light has a wavelength of _____ nm which means 0.0000004 meters. What is the frequency of violet light if light travels at 300,000,000 m/s? G U E S S

8. If it takes light 8 minutes to get to Earth from the sun, how far away is Earth from the sun? G U E S S

9. The __________ of a light wave is proportional to its energy level. Looking at your Electromagnetic Spectrum chart decide which type of electromagnetic wave is more energetic than the other. You can write the symbols < “less than” or > “greater than” in the blanks. Radio Waves _____ X-rays FM Radio _____ AM radio Short wave radio ___ Infrared Ultraviolet______ Gamma rays Television waves ____ microwaves Infrared ____ visible light waves Visible light waves _____ ultra violet Red light _____ violet light 10. For each situation decide if it is an example of refraction, reflection, diffraction or interference: _____________You see your image in a shiny spoon _____________A pencil in water looks bent _____________A peacock’s feathers seem to shimmer different colors _____________A far sighted person wears glasses to see things up close _____________In a dark room the light from an open door seems to bend around the door frame _____________A coin collector uses a magnifying glass to study a coin _____________You see clouds in a puddle of water on the ground _____________Light is shown through a small slit and creates patterns of light and dark lines _____________The moon is visible at night _____________A mirage forms in the desert sand in warmer air _____________The distance to the moon can be determined using a laser and mirrors left on the moon by astronauts. This is a tough one!_____________ and _____________You see a rainbow in the sky Label each of the two interactions you listed above for a rainbow on this picture: