<p> Name: ______Hour: ____ Date: ______Chemistry: Light Problems</p><p>Directions: Solve the following problems. Show proper set-up, work, and units for full credit. Box in your final answer. </p><p>1. A wave has a frequency of 22 Hz and a wavelength of 4.0 m. What is its velocity?</p><p>2. What is the frequency of a wave if its wavelength is 3.6 x 10–9 m and its velocity is 3.0 x 108 m/s?</p><p>3. As you move across the continuous spectrum from red to violet, what happens to…</p><p> a. wavelength?</p><p> b. frequency?</p><p>4. A beam of microwaves has a frequency of 1.0 x 109 Hz. A radar beam has a frequency of 5 x 1011 Hz. Which type of radiation…</p><p> a. has the longer wavelength?</p><p> b. is nearer to visible light in the electromagnetic spectrum?</p><p> c. is closer to X-rays in frequency value?</p><p>5. A bright line spectrum contains a line with a wavelength of 518 nm. Determine…</p><p> a. the wavelength, in meters. (Hint: 1 x 109 nm = 1 m)</p><p> b. the frequency.</p><p> c. the energy.</p><p> d. the color of the line. 6. A photon has an energy of 4.00 x 10–19 J. Find…</p><p> a. the frequency of the radiation.</p><p> b. the wavelength of the radiation.</p><p> c. the region of the electromagnetic spectrum that this radiation represents.</p><p>7. A photon of light has a wavelength of 3.20 x 105 m. Find…</p><p> a. the frequency of the radiation.</p><p> b. the energy of the photon.</p><p> c. the region of the electromagnetic spectrum that this radiation represents.</p><p>8. Determine the frequency of light with a wavelength of 4.257 x 10–7 cm.</p><p>9. How many minutes would it take a radio wave with a frequency of 7.25 x 105 Hz to travel from Mars to Earth if the distance between the two planets is approximately 8.0 x 107 km?</p><p>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 1.00 x 10–3 nm, calculate the energy of a photon of this radiation.</p><p>Selected 1. 88 m/s 5a. 5.18 x 10–7 m 5c. 3.84 x 10–19 J 6b. 4.97 x 10–7 m 7b. 6.21 x 10–31 J 9. 4.4 minutes Answers: 2. 8.3 x 1016 Hz 5b. 5.79 x 1014 Hz 6a. 6.03 x 1014 Hz 7a. 938 Hz 8. 7.047 x 1016 Hz 10. 1.99 x 10–13 J KEY</p><p>Chemistry: Light Problems</p><p>Directions: Solve the following problems. Show proper set-up, work, and units for full credit. Box in your final answer. </p><p>1. A wave has a frequency of 22 Hz and a wavelength of 4.0 m. What is its velocity?</p><p> v  f   v  20 Hz 4.0 m v  80 m/s</p><p>2. What is the frequency of a wave if its wavelength is 3.6 x 10–9 m and its velocity is 3.0 x 108 m/s?</p><p> v 3.0 108 m/s v  f    f   f  7.9 1016 Hz  3.8  10 -9 m/s</p><p>3. As you move across the continuous spectrum from red to violet, what happens to…</p><p> a. wavelength? wavelength shortens</p><p> b. frequency? frequency increases</p><p>4. A beam of microwaves has a frequency of 1.0 x 109 Hz. A radar beam has a frequency of 5 x 1011 Hz. Which type of radiation…</p><p> a. has the longer wavelength? microwave </p><p> c 3.0 108 m/s c 3.0 108 m/s microwave   radar   c  f   f 1.0 109 Hz f 5.0  1011 Hz</p><p>microwave  0.3 m radar  0.0006 m</p><p> b. is nearer to visible light in the electromagnetic spectrum? radar</p><p> c. is closer to X-rays in frequency value? radar</p><p>5. A bright line spectrum contains a line with a wavelength of 518 nm. Determine…</p><p> a. the wavelength, in meters. (Hint: 1 x 109 nm = 1 m) </p><p> 1 m  -7 x m  518 nm    5.18  10 m 1 10 9 nm </p><p> b. the frequency. c 3.0  108 m/s c  f    f   f  5.8  1014 Hz  5.18 10 -7 m/s KEY – page 2</p><p>Chemistry: Light Problems</p><p> c. the energy.</p><p>E  h  f E  6.6  10 -34 J/Hz 5.8  1014 Hz E  3.8  10 -19 J</p><p> d. the color of the line.</p><p> green or yellow-green </p><p>6. A photon has an energy of 4.00 x 10–19 J. Find…</p><p> a. the frequency of the radiation.</p><p>E 4.0 10 -19 J E  h  f  f   f  6.1 1014 Hz h 6.6 10 -34 J/Hz</p><p> b. the wavelength of the radiation.</p><p> c 3.0 108 m/s c  f         4.9 10 -7 m f 6.11014 Hz</p><p> c. the region of the electromagnetic spectrum that this radiation represents.</p><p> visible spectrum;   492 nm (blue-green color)</p><p>7. A photon of light has a wavelength of 3.20 x 105 m. Find…</p><p> a. the frequency of the radiation.</p><p> c 3.0 108 m/s c  f    f   f  937.5 Hz or 9.4 10 2 Hz  3.2  105 m</p><p> b. the energy of the photon.</p><p>E  h  f E  6.6  10 -34 J/Hz 9.4  10 2 Hz E  6.2  10 -31Joules</p><p> c. the region of the electromagnetic spectrum that this radiation represents.</p><p> power transmissions</p><p>8. Determine the frequency of light with a wavelength of 4.257 x 10–7 cm.</p><p> 1 m  x m  4.257 10 -7 cm    4.257  10 -9 m 100 cm </p><p> c 3.0 108 m/s c  f    f   f  7.05  1016 Hz  4.257  10 -9 m KEY – page 3</p><p>Chemistry: Light Problems</p><p>9. How many minutes would it take a radio wave with a frequency of 7.25 x 105 Hz to travel from Mars to Earth if the distance between the two planets is approximately 8.0 x 107 km?</p><p>7 1000 m  10 c  3.0  108 m/s x m  8.0  10 km    8.0  10 m  1 km </p><p>8.0 1010 m x sec   267 s or 4 minutes & 27 seconds 3.0 10 8 m/s</p><p>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 1.00 x 10–3 nm, calculate the energy of a photon of this radiation.</p><p>-3  1 m  -12   1.00  10 nm    1 10 m 1.0 10 9 nm </p><p> c 3.0 108 m/s c  f    f   f  3.0 10 20 Hz  1.0  10 -12 m</p><p>E  h  f  6.6 10 -34 J/Hz  3.0 10 20 Hz E  1.98 10 -13 Joules Selected 1. 88 m/s 5a. 5.18 x 10–7 m 5c. 3.84 x 10–19 J 6b. 4.97 x 10–7 m 7b. 6.21 x 10–31 J 9. 4.4 minutes Answers: 2. 8.3 x 1016 Hz 5b. 5.79 x 1014 Hz 6a. 6.03 x 1014 Hz 7a. 938 Hz 8. 7.047 x 1016 Hz 10. 1.99 x 10–13 J</p>