LDR Characteristics Apparatus
Product Code : SCL-PLE-11743
Quick Answer: The LDR Characteristics Apparatus is a bench set for studying how the resistance of a cadmium sulphide (CdS) light dependent resistor changes with illumination. A variable-intensity lamp and a millimetre scale let students set the light level by distance and work out intensity as 1/d².
Last updated: 18 October 2026
Key Features
- Light dependent resistor is a cadmium sulphide (CdS) photo-conductive cell.
- Stabilised incandescent lamp with variable intensity control.
- Integrated millimetre scale gives the lamp-to-LDR distance for calculating 1/d² intensity.
- Meters for voltage and current, so resistance can be worked out at each light level.
- Built-in regulated DC supply for biasing the LDR circuit.
Technical Specifications
| Specification | Value |
|---|---|
| Sensor | Cadmium sulphide (CdS) photo-conductive cell |
| Light source | Stabilised incandescent lamp, variable intensity |
| Distance scale | Integrated millimetre (mm) scale |
| Meters | Voltage (V) and current (I) |
| Power supply | Integrated regulated DC supply |
| Principle | Photoconductivity; inverse square law of illuminance |
How It Is Used
The lamp is set at a series of distances along the scale and, at each one, the voltage across the LDR and the current through it are read to give its resistance. Plotting resistance against 1/d² shows that the resistance of the photo-conductive cell falls as the illumination rises, an inverse relationship that can be checked across the whole range.
Frequently Asked Questions
What kind of LDR is used in the LDR Characteristics Apparatus?
A cadmium sulphide (CdS) photo-conductive cell, biased from the built-in regulated DC supply.
How is the light intensity changed in the LDR Characteristics Apparatus?
The incandescent lamp has variable intensity control, and the millimetre scale gives the lamp distance d, so relative intensity can be calculated as 1/d² using the inverse square law.
Related Physics Lab Equipment
See the full physics lab equipment range, or these related light sensor and semiconductor apparatus:
- Miniature LDR
- NORPS 12 LDR
- Simple Circuit Module Light Dependent Resistor Board
- Solar Cell Characteristics Apparatus
- LED Characteristics Apparatus
Buyers in Brunei, Cyprus, Senegal, Namibia and Costa Rica can order the LDR Characteristics Apparatus from JLab India as an export order.
For a quotation on the LDR Characteristics Apparatus, contact JLab India on +91-8569909696.
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