Chap 16-1. Light Fundamentals. What is Light?. A transverse electromagnetic wave. What is Light?. A small part of the electromagnetic spectrum The part which stimulates the retina of the human eye Visible light has wavelengths 400-700 nm. RED Longer λ Lower f Lower E. BLUE
BUT if light does pass through matter
Michelson (1926) made a more precise measurement for speed of light, c with the Michelson-Morely Experiment:
lm/m2 = lux, abbreviated lx
Note that illumination is proportional to 1/r is the illumination (illuminance) of the sphere?2
Light from a point source spreads out
over an area proportional to the
square of the distance from the source:
7. What is the illumination on a surface 3.0 m below a is the illumination (illuminance) of the sphere?
150 Watt incandescent lamp that emits a luminous flux
of 225 lm?