The energy of a photon corresponding to the visible light of maximum wavelength is approximately. Pls explain.

It is approx. 1.89eV

the energy of the photon of visible of maximum wavelength is indirectly the energy of the photon of red part of spectrum of light.. the  maximum wave length of this is 750 nm.. now find the energy of it.. answer is 3.2065 * 10^-19 joules..

Approved

visible light fall in balmers series, so in Rydberg eqn,  n1=2, asking maximum wavlength, so smallest transition, hence N2=3, there by get wavlength, and use it in e=hc/L, where l is the wavlength

In photoeletric effect...as we knowWork function (phi)=(hc)/wavelength (lambda)Here work function is the threshold energy which is demanded by the questionAnd maxm wavelength is of red colour is. 750nmHence....E=(hc)/wavelength =12400 angstrom /750 nm =1.65 eVand if calculated in joules= 3.2×10^-19