Physics 2 Quiz
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MODERN PHYSICS CONNECTIONS
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An LED emits light centered at λ=620 nm\lambda = 620 \text{ nm} (red) when forward-biased with a voltage V=2.1 VV = 2.1 \text{ V}. A second LED emits light centered at λ=450 nm\lambda = 450 \text{ nm} (blue) when forward-biased at V=2.8 VV = 2.8 \text{ V}. A student notes that the forward voltage of each LED approximates the photon energy divided by the electron charge (i.e., eV≈hc/λeV \approx hc/\lambda), and concludes that if the forward voltage is halved for each LED, the emitted photon wavelength will double.
Which of the following best evaluates the student's conclusion?
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