Across
1
Positive particle in nucleus
4
Group of similar cells
5
Force that attracts objects together
10
Biological catalyst
12
Unit of electric potential
Down
2
Push or pull on an object
3
Reddish electrical conductor
6
Path of a planet around the sun
7
Unit of power
8
Glass that splits light into spectrum
9
Smallest unit of an element
11
Form of thermal energy