LDR full form is Light Dependent Resistor — also called a photoresistor or photoconductor. An LDR is a type of resistor whose resistance decreases when light intensity increases and increases when light decreases (dark). LDRs are used in automatic street lights, cameras, and light-activated switches.
LDR full form = Light Dependent Resistor (also: photoresistor).
Resistance of LDR decreases when light intensity increases.
In darkness: very high resistance; in bright light: very low resistance.
Made from cadmium sulphide (CdS) semiconductor.
Used in: automatic street lights, cameras, burglar alarms, nightlights.
Also called: photoresistor or photoconductor.
Full Form: Light Dependent Resistor Also called: Photoresistor / Photoconductor / LDR sensor
Working Principle: • Made from semiconductor material (cadmium sulphide, CdS) • In darkness: high resistance (1 MΩ or more) • In bright light: low resistance (few hundred ohms) • Reason: photons from light excite electrons in the semiconductor, increasing conductivity • More light → more free electrons → less resistance
Characteristics: • Non-linear response: resistance changes exponentially with light • Response time: relatively slow (milliseconds to seconds) • Inexpensive and easy to use • No polarity — can be connected in either direction
Symbol: LDR symbol = resistor symbol with arrows pointing towards it (indicating light)
Uses/Applications of LDR: • Automatic street lights: turn ON in dark, OFF in daylight • Camera exposure meters: measure ambient light • Burglar alarms: detect if light beam is broken • Automatic nightlights: switch on when dark • Solar garden lights • Camera shutter speed control
LDR in a Simple Circuit: • LDR connected with resistor in a voltage divider circuit • As light changes, voltage across LDR changes • This voltage change triggers transistor/relay/microcontroller action
Other Full Forms of LDR: • Long Distance Relationship (informal/social)
LDR full form is Light Dependent Resistor (also called photoresistor). It is a semiconductor component whose resistance decreases when light intensity increases. In darkness, an LDR has very high resistance; in bright light, its resistance drops significantly. LDRs are used in automatic street lights, cameras, burglar alarms, and nightlights.
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