What Is the Energy Difference for Argon-Ion Laser Transitions?

[LebLlama]

Do you fancy argon-ion lasers??

I sure dont. =/

Homework Statement

I dont. This is a practice test problem and I cannot figure it out. Frustrating!

An argon-ion laser emits a blue-green beam of light with a wavelength of 488 nm in a vacuum. What is the difference in energy in joules between the two energy states for the atomic transition that produces this light?

a.
6.18 × 10–20 J


b.
1.05 × 10–20 J


c.
5.10 × 10–28 J


d.
4.08 × 10–19 J


e.
4.76 × 10–24 J

Homework Equations

See below. I am not sure its right though since I am not producing one of the multiple choice questions.

The Attempt at a Solution

This is what I came up with so far:
so we know the wavelength (l) of the light emitted.

now, E (energy) is h * n (h = Plancks constant, n = frequency)

so

E = h * n

but also, l = c T = c / n (T is the period of the oscillation of the emitted light) which means

n = c / l

so

E = h * c / l

with this formula E can be computed

(c = 3 * 10^8 m/s is the speed of light)
my answer isn't any of the above, however. :(

help? =)

 

[ideasrule]

Try again. The formula E=hc/l is right, and if you plug in the right numbers, it DOES give you one of the answer choices.

 

[LebLlama]

I keep getting 4.07 x 10^-28

Thats a combination of c and d haha. :(

 

[LebLlama]

Update(since I know you're all eager to hear about my adventures):

I got it! I just had to convert nm to m haha. Duh.

Oh, and I got 100% on my quiz today!WOOT WOOT!

Id start breakdancing right now out of pure joy, but I don't want to snap my legs.

This means Ill get an A for 2nd semester physics. I got an A in 1st semester too and I don't even like the subject.

*llama dance*