In this lesson, we will learn how to determine the radiant power received per unit area at a distance from a point source of electromagnetic radiation.
Q1:
A point source of electromagnetic radiation has a radiant power of 225 W. The radiation emitted by the source is all visible light, with wavelengths between 400 nm and 700 nm. Each wavelength emitted has a 1 nm difference in length to its most similar emitted wavelength. All the wavelengths are emitted with the same energy. How much radiant power is emitted at each wavelength?
Q2:
Three point sources of electromagnetic radiation are at different points on the surface of a sphere centered on the point 𝑂, as shown in the diagram. The radius of the sphere is 2.5 m. What is the irradiance at the point 𝑂?
Q3:
An object that emits electromagnetic radiation uniformly is at the position 𝑂, as shown in the diagram. Which of the following statements most correctly describes how the irradiance 𝐼 produced by the radiating object at the points 𝑃, 𝑃, and 𝑃 on the surface of a sphere centered at 𝑂 compare to each other?
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