Calculate the number of photon of light with a wavelength of 6000 Å that provide I joule of energy.

Explanation

`E=hv=(hc)/lamda=(6.625xx10^(-34)Jsxx3xx10^(8)ms^(-1))/(6000xx10^(-10)m)`
`=0.00331xx10^(-16)J=3.31xx10^(-19)J`
Number of photons `3 .31 xx 10^(-19)` J make 1 photon
1 J `=1/(3.31xx10^(-19))=0.3021xx10^(19)=3.021xx10^(20)` photons.