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.

Author: Gudal Mikree
Country: India
Language: English (Spanish)
Genre: Literature
Published (Last): 9 August 2005
Pages: 343
PDF File Size: 7.66 Mb
ePub File Size: 7.10 Mb
ISBN: 346-8-16150-563-6
Downloads: 66434
Price: Free* [*Free Regsitration Required]
Uploader: Maujora

Teacher Incharge signaturePrincipal signatureExternal signatureAcknowledgements “There are times when silence speaks so much more loudly than words of praise to only as good as belittle a person, whose words do not express, but only put a veneer over true feelings, which are of gratitude at this point of time. If incident light on a photoresistor exceeds a certain frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band.

In project, we use carbon resistance of two kilo-ohms, ohms and ohms.

Light dependent resistor(LDR) – physics investigatory project

Projedt 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. In dlr to the buzzer, one can also connect a high intensity flash light to warn the people in the neighborhood about the intrusion. When sufficient base voltage is present, the switch is on. USES By using laser, it can be used for safety purposes.

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. According to the circuit, the bulb will glow. 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.


Physics Investigatory Project LIGHT DEPENDE Submitted by | Gopinath Sah –

In mines area people face many difficulties due to absence of light in the nights. The converse is also true when light inveshigatory is reduced or cut off. We use a transformer of V for the circuit. Remember me on this computer.

Page 21 of 23 Biblography 1. The ringing buzzer wards off the intruder and also alerts the neighbors projext the intrusion.

This is the most common working principle of LDR. In this condition, whenever the light beam is intercepted by an opaque object, the LDR stops receiving the incident light and its resistance becomes high. 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.

It can be used in hilly areas. Choose a specific position for the source and mount it using a holder, make sure it is stable. Select the bulb with the lowest power rating and connect it to the holder as shown in the figure.

Physics Investigatory Project On LDR | Richard Parker –

The current will not flow through prroject LDR and the circuit wont be shunted. In this project, we use led of white colour. The LDR resistance decreases with increase in intensity of light and hence there is an increase in the flow of current. Vehicle counter at traffic check posts. Help Center Find new research papers in: If a sample of silicon has some of its atoms replaced by phosphorus atoms impuritiesthere will be ldg electrons available for conduction.


By using laser, it can be used for safety purposes. To study the variations, in current flowing in a circuit containing a LDR, because of a variation: Remember me on this computer. 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. The kilo-ohms is connected to minimise the current flow to the battery.

When no sufficient base voltage is present, oj switch is off. Enter the email address you signed up lr and we’ll email you a reset link. Since then many variants of photoconductive devices have been made. In the project, we projrct relay of 6 ohms. Measurements should be taken accurately. In project, we use 9-Volt battery.

As such we can connect many devices to the relay such as sirens, flashing lights or even an automatic dialer to the nearest police station. 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. At this time, it becomes earth, so that no voltage flows through the base of transistor T 1.

The relay is a special type of switch which is driven by its magnetic coil. Page 10 of 23 4. LDR is a resistor whose resistance decreases with increasing incident light intensity. These are used to connect components.