Across
1
Curved glass that refracts light
3
Unit of force
6
Amplified beam of light
8
Hottest planet in solar system
9
Unit of electric potential
11
Unit of energy
12
Icy body with a tail near the sun
Down
2
Form of thermal energy
4
Natural satellite of Earth
5
Center of an atom or cell
7
Nerve cell in the brain
10
Positive particle in nucleus