How do you pronounce ten to the minus 4 meters?

Answer 1

You can say "10 raised to minus 4 metres" or "10 to the power minus 4 metres".

Also, 10-4 = 0.0001 m = 0.1 mm
So, you would also be right by saying "point 1 millimeters", "zero point one millimeters" or "point 1 mm".