A particular photon has a wavelength of approximately 2x10^-7 m. What is the energy, in joules, associated with this photon?
a. 4 x 10^-32
b.1 x 10^-18
c. 1 x 10^18
d. More information is needed.
e.1.5 x 10^15

Question

A particular photon has a wavelength of approximately 2x10^-7 m. What is the energy, in joules, associated with this photon?
a. 4 x 10^-32
b.1 x 10^-18
c. 1 x 10^18
d. More information is needed.
e.1.5 x 10^15

danjs · Answer

Recall: The energy is the same as planks constant times the speed of light, divided by the wavelength

$$Energy ~of~ Photon = \frac{ h*c }{ \lambda  }$$

$$h = 6.626*10^{-34} ~J*s$$
c = 2.998 x 10^8 m/s

so

h*c = 1.99 x 10^-25 J*m

anonymous · Answer

@DanJS Thanks for the reply. In that case, I would do (1.99 x 10^-25 J*m)/( 2 x 10^-7). However, the answer would be 9.95 x 10^-19. That's where I'm confused, as that isn't one of the answer choices.

danjs · Answer

It looks like they rounded the answer, try moving the decimal one place to the left, then rounding to 1.0

anonymous · Answer

Alright, so the answer would be B.?

danjs · Answer

right

9.95 x 10^-19   =

0.995 x 10^-18 is about    

1.0 x 10^-18

anonymous · Answer

Ok, cool. Thanks alot for the help. I really appreciate it.

danjs · Answer

welcome