The primary difference between mechanical waves and electromagnetic waves is that mechanical waves need a to travel through. *
4 points
particle
medium
magnet
electrode

Medium

Explanation:

Electromagnetic waves (light, electricity) can travel through space, which has no medium (air), while mechanical waves cannot. The main medium for mechanical waves is air, and without the medium, the wave cannot travel. This is why you cannot hear sound in space.

The roaring spacecraft in Star Wars is false.

-4 on

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