Across
1
Mass per unit volume
3
Push or pull on an object
6
Absolute temperature scale unit
7
Particle of light
10
Center of an atom or cell
12
Molten rock beneath Earth surface
Down
2
Unit of energy
4
Amplified beam of light
5
Unit of force
8
Blocking of light by a celestial body
9
Gas form of a liquid
11
Infectious microscopic agent
13
Magnetic metallic element