v = Af E = hf v+Vo d2 , 2 Equations: f = f' = V- VS 10 *nm 10 nm 1 nm 10' nm 10 nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4Hz 10"2 Hz 10 9 Hz 10" Hz 101 Hz 1012 Hz 1019 Hz 10" Hz 10# Hz 10* Hz 10 Hz Visible light 7 x 10# Hz 4 X 10#* Hz If an ambulance is moving toward you and you are at rest, its siren will have... O A higher apparent frequency than actual frequency O A lower apparent frequency than actual frequency o The same frequency as actual frequency o Impossible to determinef' = v+vo 2 Equations: f = v = af E = hf d2 V-VS 10 *nm 10 3nm 1 nm 10' nm 10 nm 1 m 10' m Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4 Hz 10"2 Hz 10" Hz 10" Hz 1016 Hz 1012 Hz 1019 Hz 10 Hz 10*Hz 10' Hz 10* Hz Visible light 7 X 10" Hz 4 X 10#* Hz Which has a higher frequency, X-Rays or Microwaves? O X - rays O microwavesN Equations: f = v = Af E = hf f' = v+vo f dz N V-Vs 10 nm 10 3nm 1 nm 10'nm 10 nm 1 m 10' m Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4Hz 10"Hz 10 Hz 10" Hz 1016 Hz 1013 Hz 1019 Hz 10" Hz 10*Hz 10' Hz 10 Hz Visible light 7 x 10#4 Hz 4 X 10# Hz Which has a higher energy, X-Rays or Microwaves? o x-ray O microwaveN E = hf f' = v+Vo v = Af d2 Equations: f = V -V s d1 10 *nm 10 3nm 1 nm 10'nm 10 nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 104 Hz 10" Hz 10" Hz 10"# Hz 1016 Hz 1012 Hz 1019 Hz 10" Hz 10# Hz 10' Hz 10 Hz Visible light 7 x 10#4 Hz 4 x 10 * Hz Which has a longer wavelength, orange light or blue light? o orange o blueEquations: f = v = af E = hf f' = - v+vo d2 V -Vs d , 2 10-5 nm 10-3 nm 1 nm 10' nm 105 nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 1024Hz 1012 Hz 10 0 Hz 10" Hz 1016 Hz 1012 Hz 1019 Hz 10# Hz 10 Hz 10* Hz 103 Hz Visible light 7 X 10#4 Hz 4 X 10"4 Hz Decibels The sound intensity I may be expressed in decibels above the standard threshold of hearing lo . The expression is I(dB) = 10 10910 Intensity in Decibels The logarithm involved is just the power of ten of the sound intensity expressed as a multiple of the threshold of hearing intensity. Example: If I= 10,000 times the threshold: I(dB) = 1010910 10,00010 = 10 x 4 = 40 dB Io The factor of 10 multiplying the logarithm makes it decibels instead of Bels, and is included because about 1 decibel is the just noticeable difference (JND) in sound intensity for the normal human ear. Decibels provide a relative measure of sound intensity. The unit is based on powers of 10 to give a manageable range of numbers to encompass the wide range of the human hearing response, from the standard threshold of hearing at 1000 Hz to the threshold of pain at some ten trillion times that intensity. Another consideration which prompts the use of powers of 10 for sound measurement is the rule of thumb for loudness: it takes about 10 times the intensity to sound twice as loud. Decibel calculation Dynamic levels of music in de If sound is increased in intensity by a factor of 10,000, what is the change in decibels? 4 dB O 40 dB O 10,000 dB 0 40,000 dB2 Equations: f = v = Af E = hf f = = v+vo 1 d2 V- V'S 10 *nm 10-3nm 1 nm 10' nm 10" nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4Hz 10 2Hz 10 0 Hz 10" Hz 1016 Hz 1012 Hz 1019 Hz 10# Hz 10# Hz 10* Hz 10* Hz Visible light 7 x 1014 Hz 4 X 10"* Hz The intensity of a radio signal is 0.12 W/m at a distance of 16.0 meters from a small transmitter. At what distance will the intensity be 0.04 W/m?? 0 3m O 768 m O 27.7 m O 40,000 mv+Vo Equations: f = v = Af E = hf f' = 1 dz V - VS 10 *nm 10 3nm 1 nm 10'nm 10 nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4Hz 1012 Hz 10 0 Hz 10"# Hz 1016 Hz 1012 Hz 1019 Hz 10" Hz 10# Hz 10' Hz 103 Hz Visible light 7 x 10" Hz 4 X 10 Hz Suppose you hear a clap of thunder 7 s after seeing the associated lightning strike. The speed of light in air is 3.00 x 10 m/s. How far are you from the lightning strike ( the speed of sound waves in air is 343 m/s ). (Hint: d=vt) o 2.4 km 0 49 m O 343 m O 27 kmEquations: f = v = af E = hf v+vo f' = = -f d2 2 V - VS d , 2 10-5 nm 103 nm 1 nm 10' nm 106 nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4 Hz 10 2 Hz 10 0 Hz 10" Hz 106 Hz 1012 Hz 1010 Hz 10" Hz 10 Hz 10' Hz 10' Hz Visible light 7 X 1014 Hz 4 X 10# Hz Source receding: V fobserved = f source V + V source Hears sound of longer wavelength, Source approaching: lower frequency, lower pitch. V Stationary source fobserved = If source V - V source of frequency f source VS + Moving Hears sound of All observers source shorter wavelength, hear same higher frequency, 2' higher pitch. frequency. It is a nice sunny day and the speed of sound is 346.75 m/s. You hear an ambulance coming toward you. The frequency of the siren on the ambulance is 440 Hz, but you hear a different pitch due to the doppler effect. If the ambulance is coming toward you at 25 m/s, then what is the frequency you hear? 0 346.7 Hz O 440 Hz 0 410.4 Hz O 474.18 HzEquations: f = v = af E = hf f' = = v+vo f V- VS = 42 2 10 5 nm 10 3 nm 1 nm 10' nm 10 nm 1 m 10'm Gamma rays X rays Ultraviolet Infrared Microwaves Radio waves 10 4 Hz 1012 Hz 10 0 Hz 10"# Hz 10" Hz 1012 Hz 1019 Hz 10# Hz 10# Hz 10' Hz 10* Hz Visible light 7 X 10" Hz 4 X 10 Hz Source receding: V fobserved = f source v + V source Hears sound of longer wavelength, Source approaching: lower frequency, lower pitch. V fobserved = f source Stationary source V - V source of frequency f source VS O Moving Hears sound of shorter wavelength, All observers source higher frequency, hear same higher pitch. frequency. It is a nice sunny day and the speed of sound is 346.75 m/s. You hear an ambulance coming toward you. The frequency of the siren on the ambulance is 440 Hz, but you hear a different pitch due to the doppler effect. If the ambulance is moving away from you at 25 m/s, then what is the frequency you hear? O 346.7 Hz O 440 Hz O 410.4 Hz O 474.18 Hz