Ham Radio General Class Practice Test

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Boost your ham radio knowledge with our engaging questions and detailed explanations. Prepare effectively with our diverse study resources. Ready to ace the General Class exam?

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How is an LED biased when emitting light?

Beyond cutoff
At the Zener voltage
Reverse Biased
Forward Biased

The correct answer is: Forward Biased

An LED, or Light Emitting Diode, emits light when it is forward biased. This means that the positive voltage is applied to the anode and the negative voltage is applied to the cathode. When forward biased, the charge carriers (electrons and holes) are able to recombine within the semiconductor material of the LED. This recombination results in the release of energy in the form of light, which is how the LED produces illumination. Forward biasing is critical for the operation of an LED because it lowers the energy barrier that normally prevents charge carriers from crossing the junction in the diode. As the current flows through the LED during forward bias, it causes the semiconductor material to emit photons, resulting in visible light. Other states, such as reverse bias or being beyond cutoff, do not facilitate this light-emitting process, as they prevent current flow or do not allow for effective charge recombination necessary for light production.