What is the energy of a photon of light having a wavelength of 4.5 x 10-7 meters? (Planck’s constant is 6.626 x 10-34 joule seconds; the speed of light is 2.998 x 108 m/s)
2.9817 x 10-40 joules
4.4143 x 10-19 joules
6.6745 x 10-26 joules second
9.9456 x 10-49 joules
19.864 x 10-26 joules/second

Question

What is the energy of a photon of light having a wavelength of 4.5 x 10-7 meters? (Planck’s constant is 6.626 x 10-34 joule seconds; the speed of light is 2.998 x 108 m/s)
2.9817 x 10-40 joules
4.4143 x 10-19 joules
6.6745 x 10-26 joules second
9.9456 x 10-49 joules
19.864 x 10-26 joules/second

anonymous · Answer

Energy ($E$) is related to frequency ($\nu$) of light by Planck's constant ($h$), $E=h \nu$
The speed of any wave ($c$) is just the distance it travels (a wavelength, $\lambda$) divided by the time it takes, which is the inverse of the period which is just the frequency ($\nu$),  $c = \lambda \nu$