PhysicsChapter 8: Electric Circuits
Ldr
Introduction
An LDR, or light-dependent resistor, is a component whose resistance changes with light intensity. For a typical LDR: more light → lower resistance less light → higher resistance
Definition
How It Is Used
An LDR can act as a light sensor. It is often placed in a potential-divider circuit so that changing light intensity produces a changing output voltage.
Applications
Examples include: * automatic lighting; * light-sensitive alarms; brightness-control systems; light-level sensing.
Example
During daylight, an LDR receives strong light and its resistance falls. In darkness, its resistance rises. A control circuit can detect this change and switch another device accordingly.
Exam preparation
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Review the key facts, formulas and checks before you move on.Ldr
Sticky Notes · Quick Revision
LDR
- Light ↑
- R ↓
DARKNESS
- Darkness ↑
- R ↑
60-second revision
- Light ↑ → LDR resistance ↓.
- Light ↓ → resistance ↑.
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