## Conceptual Physics (12th Edition)

The speed of light in vacuum, c, is faster than any material object in the universe, and much, much larger than everyday speeds, even those of satellites racing around the Earth. Planck’s constant h is small because it appears in the equation that assigns wavelengths to moving objects ($\lambda = \frac{h}{p}$), and energy to individual photons (E = hf). The wavelengths of ordinary matter are billions upon billions of times too small to for us to detect. The energies of photons are also too small for us to detect individually with the naked eye. Hence, h is considered small.