Name: ______Period: ____
Electromagnetic Waves
1. Yellow light has a wavelength of 556 nm. What is its frequency?
2. A lightyear is the distance that light travels in one year (in a vacuum). What is the distance (a) in meters? (b) in miles?
3. The radius of Earth’s orbit around the Sun is, on average, 1.50 x 1011 m. How long does it take sunlight to reach the Earth?
4. (a) List the seven distinct regions of the electro magnetic spectrum in order of increasing frequency.
(b) Give the wavelength range of the portion of this spectrum to which our eyes are sensitive.
(c) List the six main color divisions in order of increasing frequency.
5. The closest star to the Earth, besides the Sun, is Alpha Centauri, which is 4.3 ly away. (a) How long does it take light to travel from Alpha Centauri to the Earth? (b) How long would it take a spaceship traveling at 100,00 km/h to reach Alpha Centauri?
6. One nanosecond (ns) is 10-9 s. Laboratory workers often estimate the distance light travels in a certain time by remembering the approximation “light goes one foot in one nanosecond.” (a) How far, in meters, does light actually travel in one nanosecond? (b) Convert this to feet.
7. The distance to the moon can be found with the help of mirrors left on the moon by astronauts. A pulse of light is sent to the moon and returns to Earth in a total time of 2.562 s. Calculate the distance to the moon.
8. The graph below shows the profile of an electromagnetic wave at a particular point in time. The units on the horizontal axis are nm and the units on the vertical axis are V/m. Find (a) the amplitude, (b) the wavelength, (c) the frequency, and (d) the period of the wave.
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9. Modern lasers can create a pulse of light that lasts only a few femtoseconds (1 fs= 10-15 s). (a) What is the length of a pulse of light that lasts 6.0 fs? (b) How many wavelengths of violet light (λ = 400 nm) are included in such a pulse?
10. Radio stations are usually identified by their frequency. One radio station in the middle of the FM band has a frequency of 99.1 MHz. What is its wavelength?
11. The radius of Earth’s orbit is about 150 million km and the radius of Mars’ orbit is about 228 million km. (a) What is the shortest amount of time that a radio signal could travel from Earth to Mars? (b) What’s the longest amount of time the radio signal could take? Assume circular orbits.