Question

1) A laser emits light of frequency 4.74 x 10# sec . What is the wavelength of the light in nm(l m -10 nm)? The speed of light is c 2.998 x 10* m/s. (5 pts) 2) The blue color of the sky results from the scattering of light by air molecules. The blue light has a frequency of about 7.5 x 10" Hz. (1 Hz- 1/s) a) Calculate the wavelength, in nm, associated with this radiation. 1 Hz 1s (5 pts) Calculate the energy, in joules, of a single photon associated with this frequency.Planck's constant, h, is 6626 x 1034 Js. (Bonus +2) b)

Answer 1

Tofind the wavelength Given that trequency-4.74x10s The speed of lightis 2998x10*m/s Use the formula Where vfrequency 2- wavelength(m) c - speed of light (constant value) 2.998x10' m/s 2.998x108 mis 4.74 x10s -6.32x10-7m Convert wavelength m to nm 1m -10° nm 6.32x10m- 6.32x10 x10 nm 632nm Hence the wavelength-632nm

Tofind the wavelength Given that frequency- 7.5x10"Hz The speed of lightis 2998x10*m/s Use the formula Where = frequency λ-wavelength (m) c- speed of light (constant value) 2.998x 10°m/s 2998x108ms-1 7.5x10"Hz(or)s -3.99x10m Convert wavelength m to nm 1m = 109 nm 3.99x107m- 3.99x107 x10 nm 399nm Hence the wavelength = 399nm

Tofind the energy Given that wavelength - 399nm Use the formula Where E energy h = Planck's constant = 6.626 × 10-34 J·s λ wavelength (m) c speed of light [constant value)-2.998x10°m/s Convert wavelength nm to m 399nm 1nm -10*m 399nm = 399 × 10-9 m 3.99x10m 6.626x 10-34J. s 2998x108 m/s 3.99x10m E -4.97x10-19j Hence the energy - 4.97x10 J