A Level Physics Practice Exam 2025 - Free A Level Physics Practice Questions and Study Guide

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.