Calculate the wavelength of a photon having energy of 1.257 X 10-24 joules.

Calculate the wavelength of a photon having energy of 1.257 X 10-24 joules. Planck’s constant is 6.626 x 10-34 joule seconds; the speed of light is 2.998 x 108 m/s)
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A.
5.10 m
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B.
6.327 m
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C.
0.324 m
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D.
0.158 m

Easy way to go from energy to wavelength or frequency is to use this applet.

http://www2.chemistry.msu.edu/faculty/re…

However for your physics homework you should know how to use a formula:

E = hc/λ where h is plank's constant, c is the velocity of light in a vacuum and λ is the wavelength of light.

Rearranging to get the wavelength:
λ = hc/E

λ = (6.626 x 10-34 joule seconds * 2.998 x 108 m/s)/1.257 X 10-24 joules

= 0.158 m

Answer is D.

E= 6.626 x 10-34 joule seconds*f
then f=1.257 X 10-24 joules/ 6.626 x 10-34 joule seconds =1.89707x10^9 sec-1
lambda=1,89707x10^9 sec-1/2.998 x 108 m/s = 6.323 m (option B)

................... E = h * c / λ

1.257 x 10^-24 = (6.626 x 10^-34) * (2.998 x 10^8) / λ

.................... λ = 0.158 m