physics project class 12th students about the physics
- 1. 1 E.S.LORDS INTERNATIONAL SCHOOL VILLUPURAM PHYSICS PROJECT ACADEMIC YEAR : 2022 – 2023 NAME : CLASS : XII ROLL NO : TOPIC : SUBMITTED BY :
- 2. 2 CERTIFICATE OF EXCELLENCE This is to certify that this Physics Investigatory Project on the topic ‘ ‘has been successfully completed by of Class XII under the guidance of in particular fulfilment of the curriculum of Central Board of Secondary Education leading to the award of annual examination of the year 2022-23. Sign of External Examiner Sign of Internal Examiner Sign of Principal
- 3. 3 ACKNOWLEDGEMENT In the accomplishment of this project successfully, many people have best owned upon me their blessings and heart pledge support, this time I am utilizing to thank all the people who have been concerned with this project. Primarily I would like to thank god for being able to complete this project with success. Then I would like to thank my principal Mr. Gunasekaran, my co-ordinator Mr.R. Markand our subject teacher Mr. A.Arunagiri whose valuable guidance has been the ones that helped us to patch this project and make it full proof success, his suggestions and instruction has served as the major contribution towards the completion of this project. Then I would like to thank my parents and my classmates who helped me with valuable suggestions for finalizing and completion of project.
- 4. 4 INDEX S.NO CONTENT PAGE 1 Aim of the project 2 About the topic 3 Introduction 4 Circuit diagram 5 Apparatus required 6 Principle and formulae 7 Procedure 8 Observation 9 Result 10 Closure
- 5. 5 AIM OF THE PROJECT To study the various factors on which the internal resistance/EMF of a cell depends
- 6. 6 INTRODUCTION There is a great need of batteries in our daily use electronic appliances and the use is increasing every day. Thus the batteries need to be made more powerful so that their potential can be increased greatly. Thus, this project report is based on practical analysis for the factors affecting the internal resistance of a cell. When internal resistance of the cell is decreased, we can increase the potential difference across it and hence make it more reliable.
- 7. 7 INTERNAL RESISTANCE: Internal resistance is defined as the resistance offered by the electrolyte of the cell to the flow of ions. Its SI unit is Ohm (Ω) For a cell of e.m.f (E) and internal resistance (r), connected to an external resistance (R) such the (I) is the current flowing through the circuit, 𝑬 = 𝑽 + 𝑰𝒓 𝑰𝒏𝒕𝒆𝒓𝒏𝒂𝒍 𝒓𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝒓 = 𝑬 − 𝑽 𝑰
- 9. 9 APPARATUS REQUIRED A potentiometer A battery Two one way keys Rheostat Galvanometer A resistance box An Ammeter A cell Jockey Connecting Wire Sand Paper
- 10. 10 PRINCIPLE The internal resistance of a cell is the resistance offered by its electrolyte to the flow of ions. The internal resistance of a cell is directly proportional to the distance between the electrodes. is inversely proportional to facing surface area of the electrodes in electrolyte. decreases with increase in temperature of electrolyte. is inversely proportional to concentration of the electrolyte. The internal resistance of a cell is given by 𝒓 = 𝑬 − 𝑽 𝑰
- 11. 11 PROCEDURE 1. Clean the ends of the connecting wires with sand paper and make tight connections according to the circuit diagram. 2. Tighten the plugs of the resistance box. 3. Check the e.m.f. of the battery and of the cell and make sure that e.m.f of the battery is more than that of the cell, otherwise null or balance point will not be obtained. To study the variation of internal resistance with distance of separation 4. Keep both the electrodes at the distance of 16cm. 5. Take maximum current from the battery, making rheostat resistance small.
- 12. 12 6. Without inserting a plug key k2. Adjust the rheostat so that a null point is obtained on the last wire in the potentiometer. 7. Determine the position of the null point accurately using a set square and measure the balancing length (l1) between the null point and the point P. 8. Next introduce plugs in both keys K1 and K2. At the same time, take out small resistance (1-5ohm) from the shunt resistance box connected in parallel with the cell. 9. Slide the jockey along a potentiometer wire and obtain the null point. 10. Measure the balancing length (L2) from end P. Record the observations. 11. Now keep the electrodes 12 cm apart.
- 13. 13 12. The remove the plugs of key K1 and K2. Wait for sometime and repeat steps 7 to 10. 13. Next, keep the electrodes 9cm apart to obtain another set of observations. OBSERVATION S.No Ammeter reading Position of null point (cm) Shunt Resistance R(Ω) Internal resistance r(Ω) With R(l1) Without R(l2) 1 0.3 660.5 35.5 1 0.94 2 0.3 660.5 77.2 2 1.77 3 0.3 660.5 108.3 3 2.51
- 14. 14 RESULT The Electromotive force of the cell is constant and is equal to E = 0.98 Volt The internal proportional of a cell is directly proportional to the separation between the electrodes. PRECAUTIONS The connections should be neat, clean and tight. The plugs should be introduced in the keys only when the observations are to be taken. The positive polls of the battery E and cells E1 and E2 should, all be connected to the terminal at the zero of the wires. The jockey key should not be rubbed along the wire. It should touch the wire gently.
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