Question: Calculate Wavelength from Intensity

[Hiyun]

Homework Statement

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]

Homework Equations

None given.

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.

 

[PeterO]

Homework Statement

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]

Homework Equations

None given.

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.

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.

 

[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

 

[PeterO]

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

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"?

 

[Nickie]

To calculate the wavelength from intensity, you can use the formula: wavelength = speed of light / frequency. In this case, the frequency can be calculated by dividing the number of waves per cm (5) by the length of one wave (in cm). This will give you the frequency in waves per cm.

Next, you can use the value for the speed of light (3 x 10^8 m/s) and convert it to mm/s (3 x 10^11 mm/s). Then, you can substitute the values into the formula to calculate the wavelength in mm.

Wavelength (mm) = (3 x 10^11 mm/s) / (5 waves/cm) = 6 x 10^10 mm

Therefore, the wavelength of the most intensive microwaves detected would be 6 x 10^10 mm.