A photon with wavelength λ is absorbed by an electron confined to a box. As a result, the electron moves from state n = 1 to n = 7.

a) Find the length of the box. Express your result using h, m, c, and lambda to represent Planck's constant, the electron's mass, the speed of light, and λ, respectively.

b) What is the wavelength of the photon emitted in the transition of that electron from the state n = 7 to the state n =2? Express your result using the same variables specified in the previous part.