)the electric potential due to a point charge is given by = ⁄ where is the charge, is the distance from and = 8.99 × 109 2 ⁄ . show, i n d e t a i l , that the si unit of electric potential is a volt. ( b ) what are equipotential lines? (c) how are equipotential lines used to obtain the electric field lines?

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

the answer is the index of refraction of the second medium is higher. i just took the test.