Frequency? Wavelength? HELP, quick question...

HI!
Need help with this quickie..

If you have a light ray with:

Wavelength: 310 nm

what's its frequency?

I tried:

310 E - 9 / 3.00E 8 = 1.03 E -15 Hz

That seems wrong to me, so can anyone help out please?

Many thanks :smile:

Reply 1

buzfvar_1

I think I found my error. Had wave speed and wavelength wrong way around. Great, wasted 30 minutes on that!

Ahh well, thanks anyway. Ciao!

Reply 2

john !!

yeah. I think of frequency and wavelength as a hiker - the wavelength is his stride length, and the frequency is how many strides he takes a second.

the result - metres per second - is his speed.

general equation of a wave's speed is:

v = f*lambda

in the case of electromagnetic waves, which all travel at the speed of light,

c = f*lambda
f = c/lambda

so yeah you got them the wrong way round (lambda = wavelength)

If you're ever not sure if you've got the equation right, a good test is to check that the equation is homogenous with respect to units.