Part D. Imagine an electric stove where a setting of 6 heats the coil, but it still appears black. When the dial is turned to 7, the coil begins to noticeably glow red, which means that the power density of the radiation at 700 nm (visibly red) surpassed a threshold. At what approximate temperature is the coil when it begins to glow red? Assume the human eye can only perceive a glow when the power density of light reaches a minimum of 10 W/m2 /μm (where y-axis units appear in the simulation in terms of megawatts (MW/m2 /μm)).
Visible light is a type of electromagnetic (EM) radiation. EM radiation has wavelike characteristics, which are periodic oscillations with a fixed distance between peaks (wavelength, λ) and a consistent number of cycles per second (frequency, ν). The interactions between matter and light are quantized in nature, which means specific packets, rather than a continuous gradient, of EM radiation are absorbed and emitted by atoms. The relationship between frequency (ν, Greek nu) and wavelength (λ, Greek lambda) can be described by the following equation:
c = λν
where c is the speed of light. The speed of light is a constant that is specified for each medium, and it has the value of 2.998 × 108 m/s in vacuum. Therefore, the frequency of light can be determined if the wavelength is known and vice versa.
The phenomenon known as blackbody radiation is the temperature-dependent emission of EM radiation. At any given temperature, a broad range of wavelengths is being emitted by materials, and the wavelength at which the emission intensity of EM radiation is highest is denoted as λmax. Both λmax and the range of wavelengths shift with temperature, as can be observed in the simulation
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