What is an LDR? (Light Dependant Resistor) - Electronics Basics 26

Summary

In this video, we explore the Light Dependent Resistor (LDR), a component whose resistance changes based on the amount of light it is exposed to. Made from semiconductor material, the LDR becomes more conductive in light, reducing resistance, and increases resistance in darkness. The video demonstrates this behavior using a multimeter. Practical applications of LDRs include use in streetlights, cameras, alarm systems, and nightlights, where they control devices based on light levels. The video concludes with a preview of a future project involving building a nightlight using an LDR, encouraging viewers to subscribe for more content.

Takeaways

• 😀 LDR (Light Dependent Resistor) is a type of resistor whose resistance changes based on the amount of light it receives.
• 😀 LDRs are made from semiconductor materials that become more conductive when exposed to light, reducing their resistance.
• 😀 The resistance of an LDR can be measured with a multimeter, showing different values depending on the light exposure.
• 😀 In low light or darkness, the resistance of an LDR increases, while in bright light, it decreases significantly.
• 😀 The LDR's resistance can drop to below 1 kΩ in strong light, and rise above 150 kΩ in complete darkness.
• 😀 The LDR's primary function is to detect light levels and adjust its resistance accordingly, which can be used in various practical applications.
• 😀 LDRs are commonly used in street lights to detect when it's dark outside, triggering them to turn on and off automatically.
• 😀 LDRs are also used in light meters for cameras to measure ambient light for proper exposure.
• 😀 They can be incorporated into alarm systems to detect changes in light or darkness.
• 😀 LDRs are versatile components used in devices that require light-sensitive control, such as night lights and other light-dependent applications.

Q & A

What is a light dependent resistor (LDR)?

A light dependent resistor (LDR), also known as a photoresistor, is a type of resistor whose resistance changes depending on the amount of light that hits it.

How does an LDR work?

An LDR works by using a semiconductor material that becomes more conductive when light hits it, which reduces its resistance.

What happens to the resistance of an LDR when exposed to light?

When an LDR is exposed to light, its resistance decreases, as the semiconductor material becomes more conductive.

How does the resistance of an LDR change in darkness?

In darkness, the resistance of an LDR increases, as the semiconductor material becomes less conductive.

What is the typical resistance range of an LDR in light and darkness?

In bright light, the resistance of an LDR can drop below 1 kΩ, while in darkness, the resistance can rise to over 150 kΩ or even higher.

What is the role of the multimeter in the demonstration of the LDR?

The multimeter is used to measure the resistance of the LDR, allowing us to observe how its resistance changes with varying light exposure.

What practical applications can LDRs be used for?

LDRs are used in applications where light is an important factor, such as in street lights, light meters for cameras, light detectors for alarms, and night lights.

Why are LDRs used in street lights?

LDRs are used in street lights to detect when it is dark outside so that the lights can turn on automatically, and similarly, they help turn the lights off when it gets light.

What happens when an LDR is covered or placed in a dark environment?

When an LDR is covered or placed in a dark environment, its resistance increases significantly, as it no longer receives light and the semiconductor material becomes less conductive.

What future topic related to LDRs will be covered in this series?

The next video will demonstrate how to make a nightlight using an LDR.