1. Oct 1, 2008

### kevinf

An instrument can detect 9450 photons of light of wavelength of 8.065 × 10^-8 m. What is the minimum amount of energy in J to which the instrument is sensitive? Express answer in scientific notation..

i have tried to use the e = (planck's constant) ( speed of light ) / (wavelenghth) but i am not sure how the photons figure is used

2. Oct 1, 2008

### Staff: Mentor

If one photon carries 10-18 J of energy, how much energy is carried by two identical photons?

3. Oct 1, 2008

### kevinf

where did you get 10^-18

4. Oct 1, 2008

### Staff: Mentor

Nowhere, it is not directly related to the question. I could as well ask "If one photon carries 1018 J of energy, how much energy is carried by two identical photons?", although that'll be quite a photon

5. Oct 1, 2008

### kevinf

so how would i know how much energy does each photon carry

6. Oct 1, 2008

### Staff: Mentor

You have already listed equation that allows calculation of the energy of a single photon.

7. Oct 1, 2008

### kevinf

so would i plug the wavelength into the equation and multiply by the number of photons and get my answer?

8. Oct 1, 2008

Exactly.