Waves, in general

QUESTIONS

4. A kid on a swing at the playground swings back-and-forth once every 3 seconds. What is the frequency and period of the swinging? The period is 3 seconds, and the frequency is 0.33 Hz.

5. Different colors of light have different wavelengths and frequencies. The reddest red has a wavelength of 700 nm. The most violet violet has a wavelength of 400 nm. All the other colors are in between. What are the frequency and period of these two colors?

      for 400nm (the violet end of the visible spectrum), f=7.5e14 Hz, T=1.3e-15sec
      for 700nm (the red end of the visible spectrum), f=4.3e14 Hz, T=2.3e-15 sec

6. The electromagnetic-wave broadcasting station WHFS broadcasts at a frequency of 99.1 MHz. What is the wavelength of that electromagnetic wave? 3.03 m

7. How much time does it take a radio wave (which is an electromagnetic wave) to travel all the way around the Earth (assuming it went in a circle)? 0.13 sec

8. Let's say a lightning bolt strikes the ground one mile away from you. (a) How long will it take the light flash to reach you? 5 microseconds (b) How much time will it take for the sound (thunder) to reach you? 5 seconds

9. Young humans can hear a range of sound frequencies from 20 Hz to 20,000 Hz. What is the range of wavelengths and wave periods young humans can hear? Range of wavelengths is 17 meters to .017 meters, and the range of periods is 0.05 sec to 0.00005 sec.

10. Measure the wavelength and amplitude of these two waves. If they both have a frequency of 30 Hz, how fast are they moving?

(a)                   (b)

11. You are running. If you take three steps per second, and each step is 70 cm long, how fast are you moving? 2.1 m/sec

12. See this spreadsheet.