# Significance of wavelength

1. Jun 19, 2010

### RajChakrabrty

1. The problem statement, all variables and given/known data

what is the physical significance of wavelength (not the definition)?

2. Relevant equations

suppose,
in photodetectors (like avalanche or p-i-n photo diodes) incident light having more wavelength,
penetrates more in the diode (particularly in depletion region : )

so, how this more penetration for higher wavelength can be described?

3. The attempt at a solution

2. Jun 20, 2010

### nickjer

How is energy of light related to wavelength? And what is the relation between this energy and the bandgap of the semiconductor?

3. Jun 20, 2010

### RajChakrabrty

light enrgy is related to its own wavelength.
Eg=hc/lambda.
lambda=wavelength.

but for more wavelength,
incident light penetrates the photo-detectors more in their depletion region.
my question is how this more penetration for more wavelength can be described,
the physical significance of it.

4. Jun 20, 2010

### nickjer

Well penetration means it isn't absorbed. So you have to think of what can cause absorption in a semiconductor and how does this relate to the energy of the light.

5. Jun 20, 2010

### Redbelly98

Staff Emeritus
A light wave can be thought of as a repeating pattern of electric and magnetic fields, propagating through space. The wavelength is related to that pattern.

6. Jun 20, 2010

### RajChakrabrty

so, what can be realised by wavelength, from this thought?
what is the difference for longer wavelength?

7. Jun 20, 2010

### Redbelly98

Staff Emeritus
Have you been taught about sine and cosine functions in school, and the period of a sine or cosine graph? Those are the concepts that come in to play here.

Since this appears to be a homework assignment, we don't just hand out answers. That's why I'm providing conceptual hints to help you think about what is going on.

8. Jun 20, 2010

### RajChakrabrty

having sine and cosine graph concept and period ....

why light having more wavelength penetrates more?
like why infrared is used for shorter distance than bluetooth?

because of shorter wavelength of infrared.
but,
why short wavelength light is unable to penetrate more?
this is my question, you can say.