College Algebra (10th Edition)

$0.0000005$ meters
We need to expand the wavelength of visible light ($5\times 10^{-7}$) as a whole number. This number is in Scientific Notation. To expand the number, we simply write the digit "5" and move the decimal to the left (because the power is negative) 7 places (because the power is -7). Therefore, we have: $5\times 10^{-7}=0.0000005$ meters