physics investigatory project- LDR. IATION ‘N LDR CONCLUSION Based on the obsewation above, it eam be cometuded that the LDR based. INTRODUCTION • A light dependant resistor(LDR) or a photoresistor or photocell . Physics Investigatory Project on LDR as Variable Resistor. Project Report Submitted On Light Dependence Resistance  Submitted By: A. Varun Class â XII Kendriya Vidyalaya no. 2 Pondicherry.

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Light dependent resistor(LDR) – physics investigatory project

It consists of emitter, base, and collector. Due to absence of positive voltage at base, emitter hasn’t negative voltage in the comparison of its base, so that transistor T 1 don’t conduct and no current flows through it. In this condition, whenever the light beam is intercepted by an opaque object, the LDR stops receiving the incident inveatigatory and its resistance becomes high. This de-energizes the relay and puts it to position-1 and the buzzer starts ringing.

A photoelectric device can be either intrinsic or extrinsic. A wire is a single, usually cylindrical, flexible strand or rod of metal.

Physics Investigatory Project On LDR | Richard Parker –

The LDR may not be perpendicular to the source. A light-emitting diode LED is a semiconductor light source. But at this time, 4V DC reach at base of transistor T 2so that emitter has highly negative voltage in lcr of its base, so that transistor T 2 highly conducts. In intrinsic devices the only available electrons are in the valence band, and hence the photon must have enough energy to excite the electron across the entire band gap.


Venkatakrishnanfor his vital support, guidance and encouragement, without which this project would not have come forth. It consists of emitter, base, and collector. People Counter at Auditoriums 4. In other words, the conductivity goes up. It can be used in frontier areas.

Conclusion Based on the observation above, it can be concluded that the LDR based electronic switch can be successfully deployed for the following invwstigatory DC is flowed in the circuit.

They gave me different ideas in making this project unique. When DC voltage comes through the base of transistor, current starts to flow through the emitter of transistor and completes the circuit to the negative end of the DC voltage.

Secondly I would also like to thank my parents and friends who helped me a lot in finalizing this project within the limited time frame. Due to use of it, we can solve above problems and can also save electricity and men’s power.

It can be used in jail lights. The experiment should be conducted in a dark room. Light Dependent Resistance [LDR] is a resistance, in which opposing power of current depends on the presence of quantity of light present, i. One of the most common uses for transistors in an electronic circuit is as simple switches.

It can be used in frontier areas. Should a need arise to destroy the project; care should be taken to dispose off the LDR properly as it contains harmful chemicals that can damage the environment. This device emits high frequency audio sounds that can damage the ears when put close to the ears or heard for prolonged period.


Projeft, prolonged exposure should be avoided which can damage the skin and eyes. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits.

Light dependent resistor(LDR) – physics investigatory project

Enter the email address you signed up invewtigatory and we’ll email you a reset link. This puts the relay switch in position-2, which cuts off the buzzer.

This extends the scope of the project to the invisible light sources such as ultraviolet and infrared. This project could have been done using a photo-voltaic cell in place of LDR but the circuit would have become complicated in the case of photocell.

Skip to main content. It can be investigatogy in mines areas.

The relay gets energized and changes the contact position from 1 to 2. In the circuit, we use the capacitor of mfd and mfd.

Needless to say, one has also to install a stealth switch that is known only to the owner so that the owner can disable it for his own entry.