Question
Which electrical component has a high resistance at low light intensity, and a low resistance at high light intensity?
Answer
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Finley
Professional · Tutor for 6 years
Answer
Light Dependent Resistor (LDR)
Explanation
The electrical component described in the question is affected by light intensity. In low light conditions, its resistance is high, but if the light intensity increases, the resistance drops significantly. This sort of component behaves this way because of the photoelectric effect - the idea that materials emit electrons when subjected to light. More specifically, the metallic surface within the component emits electrons when light photons hit the surface. The intensity of the light, then, determines the quantity of emissions of these electrons: more light translates into more electrons. More electrons, in turn, then means less resistance as electrons are what carry an electrical charge in a circuit thereby increasing the ease with which electricity can flow i.e. lower the resistance. The component that matches these characteristics is the Light Dependent Resistor (LDR), which is often used in light-detecting circuits where one needs information regarding the presence and intensity of light.