State three uses of dimensions.

Explanation:

dimension are used for

1 we check the homogeneity of a physical equation

2 drive a possible formula for a physical problem

3 To find dimensions of physical constants or coefficients.

i guess that visual aids present persuasive examples to what you are presenting, some factors would be theme (does it fit with the color, information, what you are presenting), size (can you see it, is it a big enough span of data/information), and overall look of the visual aid.

hope this : )

frequency or wavelenth of em radiation in a vacuum