Question

Question #202b2

Answer 1

I got: `2.5xx10^20` photons each second

Explanation:

I am not sure I got the data right but anyway...
You should have a wavelength `lambda=0.5xx10^-6m` and a power of `100W`. With these information we can work out the energy of one photon of emitted light as (Einstein's relationship):

`E=hf`

where `f` is the frequaency that can be found using:

`c=lambdaf`

with `c` the speed of light in vacuum. So we get for one photon:
`E=hc/lambda=6.63xx10^-34(3xx10^8)/(0.5xx10^-6)=3.978xx10^-19J`

But the power (energy per second) allows us to find the total number of photons emitted (each one with our calculated energy) as:
`n="power"/"energy of one photon"=100/(3.978xx10^-19)=2.5xx10^20`

photons per second.