What is the number of photons of light with a wavelength of 4000 pm that provide 1J of energy?

Explanation

Wavelength of light `(lamda)=4000` pm
`=4000xx10^(-12)m=4xx10^(-9)m`
According to Planck's quantum ehtoeyr, energy of a photon,
`E=Nhv=Nh(c)/(lamda)" [N=no. of photons, "h=6.626xx10^(-34)J*s,c=3.0xx10^(8)m*s^(-1)]`
`therefore N=(Exxlamda)/(hxxc)=(1Jxx(4xx10^(-9)m))/((6.626xx10^(-34)J*s)(3.0xx10^(8)m*s^(-1)))`
`=2.012xx10^(16)`.