(a) show that the heat capacity of a one-dimensional array of n coupled linear oscillators is given by cy3nkx (e - 1)2 where x hvlkt, and it is assumed that both longitudinal and transverse waves can propagate along the array. (b) evaluate this expression for cy in the low and high temperature limits.

you have to draw the persons position over there

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m