Learn more physics!
Q:
Hey, I got a question for you. Please solve it and answer it back with the right answer. It’s about Photon Energy. What is the real formula for the E=hv ? I mean, every site I look at, has different formulas and I don’t know who to trust cept’ you, cuz you seem smart. Anways, What does the "h" equal to?
- Chris (age 17)
Baltimore
A:
Chris- First, a piece of advice. Don't trust anyone too much. The Royal
Society motto is 'Nullius in Verba', which means something like
'nothing by say-so'.
Anyway, here's what we say. The photon energy is the light
frequency times Planck's constant. The frequency is often given the
name "nu", a Greek letter whch looks a lot like a "v". Planck's
constant is usually called "h". Its value is about 6.626*10^-34 Joules/
Hz. A Joule is a unit of energy, and a Hertz is a unit of frequency, so
when you multiply a frequency by h you get an energy.
I'm a little surprised that you found any formulas around that
disagree with this. Maybe they just wrote the same thing using
different symbols. (sometimes you see E = hbar*omega, but this is
really the same formula. Omega is just customarily nu times two times
pi, and hbar is h divided by two pi. It's written as a lowercase h with
a little slash through the vertical line. A lowercase Greek omega looks
a bit like a "w" with rounded lines on the bottom).
Mike W. (and Tom)
(published on 10/22/2007)
Follow-up on this answer.
