What does an LDR's resistance depend on?

An LDR, or Light Dependent Resistor, is a type of sensor whose resistance changes in response to the amount of light it receives. The fundamental principle behind an LDR is that it is made of a semiconductor material, which exhibits a decrease in resistance when illuminated. This means that higher light intensity causes the resistance of the LDR to decrease, allowing more current to flow through it.

Consequently, when the light intensity is low, the resistance is high, and when the light intensity is high, the resistance is low. This characteristic makes LDRs particularly useful in applications such as automatic lighting systems, where they can trigger lights to turn on or off based on ambient light conditions.

In contrast, the other factors mentioned—electrical current, temperature, and voltage applied—do not directly influence the inherent working principles of an LDR. While temperature can affect the overall behavior of electronic components, it is not a primary factor that determines the resistance changes in an LDR specifically. Similarly, electrical current and voltage do not dictate how light intensity affects the LDR resistance. Thus, light intensity is the correct and most relevant parameter regarding an LDR's resistance changes.