Question

How many photons of light having wavelength 420 nm are required to raise the temperature of 5.0 g H2O by 1° : Specific heat of H2O is 4.18 JK-1 g-1.

Answer 1

Explanation:

E=Nhc/lambda

E=m.c. change in temp

5×4.18×10^-3=N×6.6×10^-34×3×10^8/420×10^-9

N=4.42×10^19