However, when Thomas Young performed
his famous interference experiment in 1801, it was firmly established
that light is indeed a wave phenomenon The wavelength of visible
light was measured and found to be extremely small; for example, the
wavelength of yellow light is about 0 6 mm Because of the smallness
of the wavelength of visible light (in comparison to the dimensions of
typical mirrors and lenses), light can be assumed to approximately
travel in straight lines