PHYSICS INVESTIGATORY PROJECT 2019-20 AIM: To verify the Kirchhoff’s laws by applying them to cubical circuits to find their equivalent resistance. Subject Teacher:-Sandeep Kaur Submitted by:-Manish Kumar Board RollNO :- __________________ INDEX Certificate of Excellence Acknowledgement Introduction Apparatus Theory Procedure Followed Observation Precaution Sources Of Error Bibliography CERTIFICATE This is to certified that Manish Kumar, a student of class XII-D has successfully completed the research on the below mentioned project under the guidance of SANDEEP KAUR(subject teacher) and our physics lab expert MR. SATISH during the year 2018-19 in partial fulfillment of physics practical examination conducted by CBSE. Signature of Physics Teacher ACKNOWLEDGEMENT In the accomplishment of this project successfully, many people have best owned upon me their blessings and the heart pledged support, this time I am utilizing to thank all the people who have been concerned with project. Primarily I would thank god for being able to complete this project with success. Then I would like to thank my principle MRS. ANITA AGGARWAL, physics teacher MRS.SANDEEP KAUR and our physics lab expert MR. SATISH whose valuable guidance has been the once that helped me patch this project and make it full proof success. Their suggestions and their instruction have served as the major contributor towards the completion of the project. Then I would like to thank my parents and friends who have helped me with their valuable suggestion and guidance has been helpful in various phases of the completion of project. Last but not least I would like to thank my classmate who has helped me a lot. INTRODUCTION A Resistance Cube is one which is made up of resistances connected to the each side of the cube. It is also known as Kirchhoff’s Cube. This cube contains three different positions for finding the equivalent resistance of the cube. The Positions are: Ends connected in body diagonals Ends across face diagonal Ends across the vertices of the cube APPARATUS 1. Ammeter 2. Resistance wires 3. Voltmeter 4. Keys 5. Rheostat 6. Battery 7. Connection wires 8. Meter scale KIRCHOFF’S LAW (FIRST LAW) JUNCTION RULE: At ant node (junction) in an electrical circuit the sum of currents flowing into that is equal to the sum of currents flowing out of that node, the algebraic sum of currents in a network of conductors meeting at a point is zero. The formula is valid for complex currents. This law is based on the conservation of charge is the products of the current and the time. KIRCHOFF’S LAW(SECOND LAW) LOOP RULE: It is based on the principle of conservation of energy. It states that in any closed loop the sum of the potential droops across the resistors is equal to the E.M.F of the cell. Formula: This law is based on the conservation of energy where by voltage is defined as they energy per unit charge must be equal to the amount of energy and charge are both conserved. PROCEDURE Take equal length of resistance wire and wound them over a cube of desired edge length. Using ohms law apparatus, find the resistance of each circuit as explained below. Note: That voltmeter and ammeter readings. On dividing the former be latter, we get resistance of experimental circuit. COLOUR CODING A colour code is used to indicate the resistance value of a carbon resistor and its percentage accuracy. A set of coloured co-axial rings or bands is printed on the resistor which reveals the following facts. The first band indicates the first significance figure. The second band indicates the second significance figure. The third band indicates the power with which the above two significant figure must be multiplied to get the resistance value in ohm’s. The fourth band indicates the tolerance or the possible variation of the indicated value. If the fourth band is absent, it implies a tolerance of 20%. ACROSS BODY DIAGONAL CUBE-1 Edge of cube________ Voltage(V) Current(A) Resistance(OHMS) MEAN R=________Ω Rne t = (5/6)R=________Ω CUBE-2 Edge of cube ________ Voltage(V) Current(A) MEAN R=________Ω Resistance(OHMS) Rne t = (5/6)R=________Ω CUBE-3 Edge of cube ________ Voltage(V) Current(A) MEAN R=________Ω Rne t = (5/6)R=________Ω PERCENTAGE ERRORS Cube-1 Cube-2 Resistance(OHMS) Cube-3 ACROSS FACE DIAGONAL CUBE-1 Edge of cube________ Voltage(V) Current(A) Resistance(OHMS) MEAN R=________Ω Rne t = (3/4)R=________Ω CUBE-2 Edge of cube ________ Voltage(V) Current(A) Resistance(OHMS) MEAN R=________Ω Rne t = (3/4)R=________Ω CUBE-3 Edge of cube ________ Voltage(V) Current(A) MEAN R=________Ω Rne t = (3/4)R=________Ω PERCENTAGE ERRORS Cube-1 Cube-2 Resistance(OHMS) Cube-3 ACROSS THE VERTICES OF AN EDGE CUBE-1 Edge of cube________ Voltage(V) Current(A) Resistance(OHMS) MEAN R=________Ω Rne t = (7/12)R=________Ω CUBE-2 Edge of cube ________ Voltage(V) Current(A) Resistance(OHMS) MEAN R=________Ω Rne t = (7/12)R=________Ω CUBE-3 Edge of cube ________ Voltage(V) Current(A) MEAN R=________Ω Rne t = (7/12)R=________Ω PERCENTAGE ERRORS Cube-1 Cube-2 Resistance(OHMS) Cube-3 OBERVATIONS Least count of Voltmeter__________ Least count of Ammeter___________ Voltage(V) Current(A) MEAN R=________Ω Resistance: RESULT Resistance(OHMS) PRECAUTIONS Key should not be inserted when reactions are to be taken. The resistance should be equal length. All connections should be made tight. Connecting wires should be properly rubbed with sand. SOURCES OF ERROR The resistivity of the wire is not accurate. Connections may not be tight. High voltage may be used due to which short circuit may occur. BIBLIOGRAPHY Class XII-Physics NCERT-Part 1. Wikipedia.com Ask me .com You Tube