Question

In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of `3.15xx10^(-18)J` from the radiations of `600 nm`, calculate the number of photons received by the detector.

Answer 1

Where, `lambda =` wavelength of radiation
h = Planck’s constant
c = velocity of radiation
Substituting the values in the given expression of E:
`E = ((6.626 xx 10^(-34) Js)(3 xx 10^(8) ms^(-1)))/((600 xx 10^(-9) m))`
`E = 3.313 xx 10^(-19) J`
Energy of one photon `= 3.313 xx 10^(-19) J`
Number of photons received with `3.15 × 10^(-18) J` energy
`= (3.15 xx 10^(-18)J)/(3.313 xx 10^(-19) J)`
`= 9.5`
`~~ 10`