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

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

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

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

Easier Problem Solving 1.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.

Easier Problem Solving 1.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 V = f λ 340m/s = 3000Hz(λ) 0.113m = (λ) 3000 Hz V = 340m/s f = 3000 Hz λ = ? Range: 0.113m – 6.8m

Mediumier Problem Solving 2.What is the frequency of a red light with a wavelength of 650nm. (remember, the speed of light is 3x10 8 m/s)

Mediumier Problem Solving 2.What is the frequency of a red light with a wavelength of 650nm. (remember, the speed of light is 3x10 8 m/s) c = f λ m/s = f (6.50x10 7 m) 4.62 x = f c = 300,000,000m/s f = ? λ = 650nm 6.50 x10 -7 m 650nm x m = 6.50x10 -7 m ( m) 1nm

Mediumier Problem Solving 3.What is the wavelength of the FM radio station “94.5 HJY” --- its frequency is 94.5MHz.

Mediumier Problem Solving 3.What is the wavelength of the FM radio station “94.5 HJY” --- its frequency is 94.5MHz. c = f λ 3x10 8 m/s = (94.5x10 6 Hz) λ 3.17m = λ c = 3x10 8 m/s f = 94.5 MHz λ = ? 94.5 x10 6 Hz 94.5MHz x 10 6 Hz = 94.5x10 6 Hz (or 9.45x10 7 Hz) 1MHz

1.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). 2.The red light emitted by a He-Ne laser has a wavelength of 633 nm in air and travels at 3.00x10 8 m/s. Find the frequency of the laser light. 3.What is the frequency of a sound wave produced by a flute playing C-note if the wavelength is 21m? 4.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 = 4.74x10 19 Hz The answer should be f = 16.2 Hz The answer should be λ= m