1. Explain how the Greeks knew that the Earth is sphericai.
4. Explain how the photon concept and the fact that the energy of a photon is directly proportional to its frequency can be used to explain why the red lights is used in photographic dark rooms, why we get easily sunburned in ultraviolet light but not in visible light, and how we see colors.
4. Explain how the photon concept and the fact that the energy of a photon is directly proportional to its frequency can be used to explain why the red lights is used in photographic dark rooms, why we get easily sunburned in ultraviolet light but not in visible light, and how we see colors.
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1. During a lunar eclipse, when the Earth is between the sun and the moon, they identified the shadow of the Earth on the moon. As the shadow moves across the moon it is clearly round. This would suggest that the Earth is a sphere.
When light (composed of photons with different frequency and wavelength) falls on a material, some of it gets absorbed and some get reflected depending upon the color of the material on which it strikes.
Darkrooms use red lighting to allow photographers to control light carefully,so that light-sensitive photographic paper would not become overexposed and ruin the pictures during the developing process..
The amount of energy is directly proportional to the photon's electromagnetic frequency and thus, equivalently, is inversely proportional to the wavelength.