A Level Physics Practice Exam

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Study for the A Level Physics Exam. Our quiz features flashcards and multiple choice questions, each with hints and explanations. Prepare thoroughly!

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What does the acronym LDR stand for in physics?

Light Dependent Resistor
Lumen Dependent Resistor
Low Damage Resistor
Linear Dependent Resistor

The correct answer is: Light Dependent Resistor

The acronym LDR stands for Light Dependent Resistor. An LDR is a type of resistor whose resistance decreases with increasing incident light intensity. This property makes LDRs useful in various applications, such as light sensors, automatic lighting systems, and outdoor clocks, where they can help control devices based on the amount of ambient light present. When light falls on the LDR, it allows more current to flow through, which alters the resistance of the component based on the amount of light exposure. This characteristic is pivotal in applications like street lighting, where the lights turn on at dusk and turn off at dawn, utilizing the changes in light conditions. Other options provided do not accurately describe the function or characteristics of an LDR. For example, "Lumen Dependent Resistor" incorrectly focuses on lumens, a unit of light output rather than resistance change with light intensity. "Low Damage Resistor" does not relate to the fundamental function of the device, and "Linear Dependent Resistor" does not accurately convey its sensitivity to light exposure.