# Question: Calculate Wavelength from Intensity

1. Jun 18, 2013

### Hiyun

1. The problem statement, all variables and given/known data
Question: Calculate the wavelength in mm of the most intensive microwaves

Question before: State the intensity of the most intensive microwaves detected
Answer: 380 Units. (5 Waves per CM)
[Read from a graph]

2. Relevant equations

None given.

3. The attempt at a solution

I have never attempted a question to calculate wavelength from intensity. After some quick research on the internet, information about photons etc which I had never come across before showed up. If anyone would like to explain, i'd be very grateful.

2. Jun 18, 2013

### PeterO

This sounds like a microwave equivalent of a common optics question.

There is a formula of calculating the energy associated with a photon of Red light, and a photon of blue light (one is bigger than the other).

Thus if you have a 6W red light and a 6W blue light (6 joules given off each second), then there will be different numbers of photons given off by each light.
If one phonon has 0.5 J of energy, you need 12 per second, while if the other photon has 0.6 J of energy, you need only 10 per second.

Perhaps that example/concept will help.

3. Jun 19, 2013

### Hiyun

I did more research into this and I found out that Wavelength=HC/E

But i'm still stuck on getting the E (energy of a photon)

So far I've got

WL=1.99x10-25 J-m x E

4. Jun 19, 2013

### PeterO

In your original post you said the nswer to the previous question was
Answer: 380 Units. (5 Waves per CM) which you got from a graph.

Using the scale of that graph what is a "unit"?