How do i solve the following problem, i don't have an equation?

Question

A neon lamp emits red light of frequency f. How many photons are emitted by a 100 W neon light during a time period of 5 seconds (h=Planck's constant)?

Answer 1

Just putting values in Mr. Bekki's answer:

N= 100x5/[6.6x10-34x4.13x10^14]

   = 1.834x10^21 photons

Answer 2

actualy it is a tough question.

some thing is missing here

Answer 3

The energy of a single photon of frequency nu is:

E = h nu, where h is planck's constant.

The average power of an energy, E, over a time, t, is:

P = E / t

So the total energy is:

E = P t = N h nu,

where N is the number of photons.

Solve for the number of photons:

N = P t / (h nu)

They give you the power, time, and frequency.  Look up Planck's constant.  Plugnchug.

Actually, they don't give you the frequency--they just call it f (I called it nu).  So you'll have to leave the formula as is or look up the red frequency of a neon lamp or just look at a spectrum and take a wag--a red frequency is about 4.3E+14 hz.