# Homework Help: Compton effect?

1. Oct 26, 2005

### asdf1

for the following question:
for electromagnetic waves A of wavelength 10pm and electromagnetic waves B o f wavelengthh 20 pm, which produces more pronounced Compton effect?

my problem:
the question doesn't give the scattering angle or final wavelength, so isn't this question too ambiguous?

2. Oct 26, 2005

### Tide

The final wavelength depends on the scattering angle so why not compare how they each scatter from a given particle starting at rest?

3. Oct 27, 2005

### asdf1

can you explain what do you mean by that?

4. Oct 27, 2005

### Tide

The change in wavelength in Compton scattering is:

$$\Delta \lambda = \frac {h}{m_e c} \left( 1 - \cos \theta \right)$$

where $\theta$ is the scattering angle. You can use that to compare the change in energy of the photons to determine which produces a "more pronounced Compton effect."

5. Oct 28, 2005

### asdf1

but delta lamda and cos(cita) are both variables!!!

6. Oct 28, 2005

### Tide

7. Oct 28, 2005

### asdf1

maybe my english isn't too good~
i still don't understand what you mean...
@@a

8. Oct 28, 2005

### Astronuc

Staff Emeritus
How about - the greater the photon energy, i.e. shorter the wavelength, the more momentum the photon has - p = E/c.

Think of conservation of momenutm and energy.

9. Oct 29, 2005

### asdf1

@@a
i thought you also had to consider what type of material it hits, because doesn't compton effect has a range?

10. Oct 29, 2005

### Tide

Your original question was which photon produces a more pronounced Compton effect? Logically, you will keep all other variables the same and only consider what effect the wavelength has on the scattering.

11. Oct 30, 2005

### asdf1

i see... so that would be B wavelength produces the more pronouced Compton effect right?

12. Oct 30, 2005

### Tide

No. The shorter wavelength will produce a more pronounced effect -- BUT -- you have to SHOW it! E.g. calculate how much energy is transferred to the charged particle. You have the basic relations here so you should be able to do that.

13. Oct 31, 2005

### asdf1

ok, i get it! thanks!!! :)