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F.4 Phy 20 point !!!
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1. A wave has a frequency of 22 Hz and a wavelength of 4.0m. What is its velocity?2. What is the frequency of a wave if its wavelength is 3.6x10^-9 m and its velocity is 3.0x10^8 m/s ?3. As you move across the continuous spectrum from red to violet, what happens to... (a). wavelength? (b)... 顯示更多 1. A wave has a frequency of 22 Hz and a wavelength of 4.0m. What is its velocity? 2. What is the frequency of a wave if its wavelength is 3.6x10^-9 m and its velocity is 3.0x10^8 m/s ? 3. As you move across the continuous spectrum from red to violet, what happens to... (a). wavelength? (b) frequency? 4. A beam of microwaves has a frequency of 1.0x10^9 Hz. A radar beam has a frequency of 5x10^11 Hz. Which type of radiation... (a) has the longer wavelength (b) is nearer to visible light in the electromagnetic spectrum (c) is closer to X-rays in frequency value 5. A bright line spectrum contains a line with a wavelength of 518 nm. Determine... (a) the wavelength, in meter (b) the frequency (c) the energy (d) the color of the line 6. A photon has an energy of 4.00x10^-19 J. Find... (a) the frequency of the radiation (b) the wavelength of the radiation (c) the region of the electromagnetic spectrum that this radiation represents. 7. A photon of light has a wavelength of 3.20x10^5 m. Find... (a) the frequency of the radiation (b) the energy of the photon (c) the region of the electromagnetic spectum that this radiation represents. 8. Determine the frequency of light with a wavelength of 4.257x10^-7 cm. 9. How many min would it take a radio wave with a frequency of 7.25x10^5 Hz to travel from Mars to Earth if the distance between the two planets is approximately 8.0x10^7 km 10. Cobalt-60 is an artificial radioisotope that is produced in a nuclear reactor for use as a gamma-ray source in the treatment of certain types of cancer. If the wavelength of the gamma radiation from a cobalt-60 source is 1.00x10^-3 nm, calculate the energy of a photon of this radiation.
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(1) Using v = fλ, we have v = 88 m/s (2) Using v = fλ, we have f = 8.33 x 1016 Hz (3a) λ decreases (b) f increases (4a) Microwave has a longer wavelength since its frequency is lower. (b) Visible light has a frequency of order 1014 Hz, so radar is closer. (c) X-ray has a frequency of order 1016 to 1019 Hz, so radar is closer. (5a) 5.18 x 10-7 m (b) 3 x 108/(5.18 x 10-7) = 5.79 x1014 Hz (c) E = hf where h is Planck constant = 6.63 x 10-34 Js E = 3.84 x 10-19 J (per photon) (d) Around yellow to green. (6a) E = hf f = 4 x 10-19/(6.63 x 10-34) = 6.03 x 1014 Hz (b) λ = 3 x 108/(6.03 x 1014) = 4.97 x 10-7 m (c) Visible light (Wavelength ranges from 400nm to 700 nm) (7a) f = 3 x 108/(3.2 x 10-5) = 9.375 x 1012 Hz (b) E = hf = 6.63 x 10-34 x 9.375 x 1012 = 6.22 x 10-21 J (c) Microwave (8) λ = 4.257 x 10-9 m f = 3 x 108/(4.257 x 10-9) = 7.047 x 1016 Hz (9) 8 x 1010/(3 x 108) = 266.7 s = 4.44 mins (10) λ = 10-12 m f = 3 x 108/(10-12) = 3 x 1020 Hz E = 6.63 x 10-34 x 3 x 1020 = 1.989 x 10-13 J
其他解答:
1. By v = f入 Velocity, v = (22)(4.0) = 88 m/s 2. f = v/入 = (3.0 X 10^8)/(3.6 X 10^-9) = 8.33 X 10^16 Hz 3. The wavelength will decrease. The frequency will increase. 2009-12-02 10:13:59 補充： 4.a. For EM waves, the longer the wavelength, the lower the frequency. So, microwaves have a longer wavelength. b. The frequency of visible light is in the order of 10^14 Hz, so radar beam is nearer to it. c. X-rays has the order of 10^16 Hz in frequency, so radar beam is nearer. 2009-12-02 10:14:10 補充： 5.a. Wavelength = 518 X 10^-9 m b. f = v/入 = (3.0 X 10^8)/(518 X 10^-9) = 5.79 X 10^14 Hz c. Energy = hf = (6.63 X 10^-34)(5.79 X 10^14) = 3.84 X 10^-19 J d. The color is yellow. 2009-12-02 10:14:22 補充： 6.a. E = hf 4.00 X 10^-19 = (6.63 X 10^-34)f Frequency, f = 6.03 X 10^14 Hz b. 入 = v/f = (3.0 X 10^8)/(6.03 X 10^14) = 4.97 X 10^-7 m c. The region is blue. 2009-12-02 10:14:33 補充： 7.a. f = v/入 = (3.0 X 10^8)/(3.20 X 10^5) = 937.5 Hz b. Energy, E = hf = (6.63 X 10^-34)(937.5) = 6.22 X 10^-31 J c. The region is the radio wave. 8. Frequency, f = v/入 = (3.0 X 10^8)/(4.257 X 10^-7 X 10^-3) = 7.05 X 10^17 Hz 2009-12-02 10:14:38 補充： 9. The speed of EM wave is 3.0 X 10^8 m/s, no matter how large is its wavelength. Required time, t = d/v = (8.0 X 10^10)/(3.0 X 10^8) = 267 s = 4.44 mins 10. Energy, E = hf = hv/入 = (6.63 X 10^-34)(3.0 X 10^8)/(1.00 X 10^-3 X 10^-9) = 1.99 X 10^-13 J
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