Across
1
Force that attracts objects together
4
Reddish electrical conductor
6
Tissue that contracts for movement
7
Nerve cell in the brain
Down
2
Particle of light
3
Path of a planet around the sun
5
Unit of electric potential
6
The Red Planet
8
Curved glass that refracts light
9
Second lightest element
10
Magnetic metallic element
11
Mass per unit volume