Wave practice!
Work out in your notes. These will be reviewed on Monday.
Recall also:
v = (frequency)(wavelength)
c = 3 x 108 m/s (speed of light, including any type of electromagnetic wave)
1. What is the wavelength of the radio station 97.9 ("98 Rock"). Keep in mind that the number refers to the frequency in MHz, and note that MHz means 'million (x 106) Hz."
2. The visible range of human eyesight is 700 nm to 400 nm. What are the frequencies associated with this, and which end is red and which is violet?
3. Find the speed of a 500 Hz wave with a wavelength of 0.4 m.
4. What is the frequency of a wave that travels at 24 m/s, if 3 full waves fit in a 12-m space? (Hint: find the wavelength first.)
5. Approximately how much greater is the speed of light than the speed of sound?
6. Harmonics
a. Draw the first 3 harmonics for a wave on a string.
b. If the length of the string is 0.5-m, find the wavelengths of these harmonics.
c. If the frequency of the first harmonic (n = 1) is 15 Hz, find the frequencies of the next 2 harmonics.
d. Find the speeds of the 3 harmonics.
7. (Review) Differentiate between mechanical and electromagnetic waves. Give examples.
8. The note C vibrates at 262 Hz (approximately). Find the frequencies of the next two C’s (1 and 2 octaves above this), and the frequency of the C below it.
9. A red LED has a wavelength of 662 nm. What is the frequency of light emitted from it? (nm refers to x 10-9 m)
10. Concert A is defined as 440 Hz. What are the frequencies of:
a. A#, which is one semi-tone above A?
b. C, which is three semi-tones above A?
c. A-flat, which is one semi-tone below A?
(Recall that a semi-tone is the same as a piano key or guitar fret.)
10. Concert A is defined as 440 Hz. What are the frequencies of:
a. A#, which is one semi-tone above A?
b. C, which is three semi-tones above A?
c. A-flat, which is one semi-tone below A?
(Recall that a semi-tone is the same as a piano key or guitar fret.)
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