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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Modern light dependent resistors are made of materials such as lead sulphide, lead selenide, indium antimonide and most commonly cadmium sulphide CdS and cadmium selenide. These photons in the incident light should have energy greater than the band gap of the semiconductor material to make the electrons jump from the valence band to the conduction band.

It can be used in hilly areas. A light-emitting diode LED is a semiconductor light source.

Physics Investigatory Project On LDR | Richard Parker –

The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits Photoconductivity. When this is exposed to light a change in resistance is noted. But when the light source is switched on, the resistance of LDR falls and this drives the transistor switching circuit and the relay gets energized. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits.

Moreover, unique photoresistors may react substantially differently to photons within certain wavelength bands. In this project, we use led of white colour. Photoconductivity – the mechanism behind the photoresistor – results from the generation of mobile carriers when photons are absorbed by the semiconductor material used for the photoconductor. It can be used to find the intensity of sunlight falling on the LDR. In the project, common emitter n-p-n transistor BC is used.


Keeping all the lamps at a fixed distance. It can be used in mines areas.

Light dependent resistor(LDR) – physics investigatory project

Enter the email address you signed up with and we’ll email you a reset link. In the circuit, we use the capacitor of mfd and mfd. The relay has two positions. 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.

In the circuit, we use the capacitor of mfd and mfd. These are used to connect components. Thus energy is saved by ensuring the light is only on during hours of darkness.

When no light falls on the LDR, the LDR offers very low resistance nearly 10 ohms and the circuit is shunted and therefore the led doesnt glow. When DC voltage comes through the base of transistor, the current starts to flow through the emitter of transistor and completes the circuit to the negative end of the DC voltage. In a photocell, when it is excited by light photonselectricity is generated.

Light dependent resistor(LDR) – physics investigatory project

Lxr T 1 and resistance of 1. Help Center Find new research papers in: When no sufficient base voltage is present, the switch is off.

The cost of circuit is low. The circuit uses two transistors, connected in series. An opening was cut on the box to present a door.

Click here to sign up. A photoresistor is made of a high resistance semiconductor.

Alka Chopra as well as our principal R K Tyagi who gave me the golden opportunity to do this wonderful project on the topic Write the topic namewhich also helped me in doing a lot of Research and i came invsstigatory know about so many new things I am really thankful to them. Help Center Find new research papers in: The transistor circuit described later is connected to a relay which is om turn connected to an external buzzer.

  IEC 60571 PDF

This type of photoresistor uses a photoconductive material that involves excitation of charge carriers between an impurity and the valence band or conduction band. Now, the above terminal of 1.

From 3V approximate 1. Another end of the kilo-ohms resistor is connected to the emitter. Similarly switch to current section and move to micro ampere in the multimeter.

Page investigatoru of 23 Biblography 1. Light Dependent Resistance [LDR] is a resistance, in which opposing power of current depends on the presence of quantity of light present, i. Therefore the circuit is not complete and the led will not glow. For solve above these problems, we create a device in which the lights glow in night and in day time, they off automatically and don’t glow.

In the project, INdiode is used. 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. This project could have been done using a photo-voltaic cell in place of LDR but the dlr would have become complicated in the case of photocell.

Applications The internal components of a photoelectric control for a typical American streetlight. Skip to main content.