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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But at this time, emitter has some negative voltage in the comparison of its base. LDR means light dependent resistance which is used to complete the circuit.

These resistors use pure semiconductors like silicon or germanium. In this way transistor T 1 conduct and current start to flow in transistor T 1.

Behind the door, a light source is placed and in the line of vision of the light source, an LDR is also placed. They gave me different ideas in making this project unique. Ld a Dark sensor using L.

Light dependent resistor(LDR) – physics investigatory project

Applications The internal components of a photoelectric control for a typical American streetlight. Skip to main content. Photoresistor mechanism A photoresistor or photocell is a component that uses a photoconductor between two contacts.

I would also like to express my gratitude to the staff of the Department of Physics at Lrr Vidyalaya Pondicherry university campus for their support during the making of this project.


Light dependent resistor(LDR) – physics investigatory project

Thus, when there is no light on the LDR, the transistor remains un-fired. The kilo-ohms is connected to minimise the current flow to the battery. Vehicle counter at traffic check posts. 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. projecg

Light Dependent Resistance, Physics Project Report Light Dependent Resistance, Project Report LDR

nivestigatory The resulting free electrons and their hole partners conduct electricity, thereby lowering resistance.

An opening was cut on the box to present a door. Modern light pfoject resistors are made of materials such as lead sulphide, lead selenide, indium antimonide and most commonly cadmium sulphide CdS and cadmium selenide. This extends the scope of the project to the invisible light sources such as ultraviolet and infrared. But at this time, 4V DC reach at base of transistor T 2so that emitter has highly negative voltage in comparison of its base, so that transistor T 2 highly conducts.

We use a transformer of V for the circuit. Light Dependent Resistance [LDR] is a resistance, in which opposing power of invvestigatory depends on the presence of quantity of light present, i.

Click here to prjoect up. Enter the email address you signed up with and we’ll email you a reset link. It can be used in hilly areas. In short, a transistor conducts current across the collector- emitter path only when sufficient voltage is applied to its base.


There is an increase in the current as the distance from the source decreases. Page 21 of 23 Biblography 1. Photoconductivity – the mechanism behind the photoresistor – results from the generation of mobile carriers when photons are absorbed by the semiconductor prkject used for the photoconductor.

Distance between Source Bulb S. Moreover, unique photoresistors may react substantially differently to photons within certain wavelength bands. The collector of transistor T 1 has positive voltage because 6V DC pass through 1. For this, we have to simply replace the buzzer with a digital counter.

Page 13 of 23 Photoresistors can be placed in streetlights to control when the light is on.

A photoelectric device can be either intrinsic or extrinsic. An intrinsic semiconductor has its own charge carriers and is not an efficient semiconductor, for example, silicon.

It can be used in frontier areas. This type of photoresistor uses a photoconductive material that investibatory excitation of charge carriers between an impurity and the valence band or conduction band.

From 3V approximate 1.

This gives the value of the current.