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.

Explanation

Total energy received `=3.15xx10^(-18)J`
`lambda = 600 nm = 600 xx 10^(-9)m = 6xx10^(-7)m`
Energy of one photon , E`=(hc)/(lambda)=((6.626xx10^(-34)Js)xx(3xx10^(8)ms^(-1)))/((6xx10^(-7)m))`
`=3.3125xx10^(-19)J`
`:. " "`No. of photons `=((3.15xx10^(-18)J))/((3.3125xx10^(-19)J))=10`