If the wavelength of electromagnetic radiation is doubled, what happens to the energy of photon ?

Explanation

Photon energy (E) =hv=`(hc)/(lambda)`
`E prop (1)/(lambda)`
Given `lambda_(1)=lambda, lambda_(2)=2lambda,E_(1)=E`
`(E_(1))/(E_(2))=(lambda_(2))/(lambda_(1))`
`(E)/(E_(2))=(2lambda)/(lambda)`
`E_(2)=E//2`
`therefore ` The energy of photon reduces to half to its initial value.