1. Waves & Wave Properties Sound Waves & Light Waves Problem Solving
Unit 07
Waves & Wave Properties
Sound Waves & Light Waves
Problem Solving

2. Speed of light = frequency x wavelength
REVIEW
Wave Speed Equation
V=f λ
velocity = frequency x wavelength
c =f λ
Speed of light = frequency x wavelength

3. v = 340 m/s c = 300,000,000m/s Sound needs a medium to travel
Speed of Sound in standard air:
Light can travel through a vacuum Speed of Light in a vacuum:
v = 340 m/s
c = 300,000,000m/s

4. What is the relationship between speed, frequency and wavelength?
The only way to change the speed of the wave is to _______________________.
A change in the frequency will change _____________.
A change in the wavelength will change ___________.
To change the medium
wavelength
frequency

5. Easier Problem Solving
A guitar emits frequencies that range from a low of about 50Hz to a high of about 3000Hz. Find the range of wavelengths in air attained by this instrument when the speed of sound is air is 340m/s.

6. Easier Problem Solving
A guitar emits frequencies that range from a low of about 50Hz to a high of about 3000Hz. Find the range of wavelengths in air attained by this instrument when the speed of sound is air is 340m/s.
V=f λ
340m/s = 50Hz(λ)
6.8m = (λ)
V = 340m/s
f = 50 Hz
λ = ?
50 Hz
50 Hz
Range:
0.113m – 6.8m
V=f λ
340m/s = 3000Hz(λ)
0.113m = (λ)
V = 340m/s
f = 3000 Hz
λ = ?
3000 Hz
3000 Hz

7. Mediumier Problem Solving
What is the frequency of a red light with a wavelength of 650nm. (remember, the speed of light is 3x108m/s)

8. Mediumier Problem Solving
What is the frequency of a red light with a wavelength of 650nm. (remember, the speed of light is 3x108m/s)
c = 300,000,000m/s
f = ?
λ = 650nm
650nm x 10-9m = 6.50x10-7m ( m)
1nm
c =f λ
m/s = f (6.50x107m)
4.62 x 1014= f
6.50 x10-7 m
6.50 x10-7 m

9. Mediumier Problem Solving
What is the wavelength of the FM radio station “94.5 HJY” --- its frequency is 94.5MHz.

10. Mediumier Problem Solving
What is the wavelength of the FM radio station “94.5 HJY” --- its frequency is 94.5MHz.
c = 3x108m/s
f = 94.5 MHz
λ = ?
94.5MHz x 106Hz = 94.5x106 Hz (or 9.45x107Hz)
1MHz
c =f λ
3x108m/s = (94.5x106 Hz) λ
3.17m = λ
94.5 x106 Hz
94.5 x106 Hz

11. What is the minimum frequency of sound waves required for the bat to detect an insect that would reflect a wavelength of m? (Assume the speed of sound is 340m/s).
The red light emitted by a He-Ne laser has a wavelength of 633 nm in air and travels at 3.00x108m/s. Find the frequency of the laser light.
What is the frequency of a sound wave produced by a flute playing C-note if the wavelength is 21m?
What is the wavelength of a radar signal that has a frequency of 33 GHz?
The answer should be f = Hz
The answer should be f = 4.74x1019 Hz
The answer should be f = 16.2 Hz
The answer should be λ= m

12. PRACTICE COMPLETE THE ATTACHED WORKSHEET. PLEASE NOTE:
The Period (T) represents the time it takes one point in a wave to travel one wavelength. T=1/f
Velocity is the rate of change in an object’s position. V=d/t (with d being the distance travelled)