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Photoelectric Effect. February 11 and 12. Question. Why do photographers use red light in their darkrooms? The low-energy photons in red light do not affect photographic film. The Photoelectric Effect. Photoelectric effect: experiment showing light is also a particle.
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Photoelectric Effect February 11 and 12
Question • Why do photographers use red light in their darkrooms? • The low-energy photons in red light do not affect photographic film.
The Photoelectric Effect • Photoelectric effect: experiment showing light is also a particle.
Photoelectric effect experiment • Two metal plates in vacuum, shine light on one plate. Measure current between plates
The photoelectric effect • The ejection of electrons from certain metals when light falls upon them. • High-frequency light was capable of ejecting electrons; yet low-frequency light could not dislodge electrons. • This result is not explained by light as waves but is explained by light as particles (a stream of photons).
Mirror Image • How do we have our image in a mirror? p q h h’
Size of Mirror • How big should a mirror be in order to have the image of your whole body?
Polarization of Light Waves Light consists of waves oscillating in random directions. Light of this sort is unpolarized. Vertical polarizer produces a beam of light with waves oriented in the same direction.