Internal resistance of a cell pdf

Electromotive Force IV. Objective V. Apparatus VI. Circuit Diagram VII. Theory VIII. Procedure IX. Observations X. Conclusions XI. Precautions XII. Sources of error XIII. Bibliography XIV. Manjusha Rawat Subject teacher. This project is absolutely genuine and does not indulge in plagiarism of any kind.

The references taken in making this project have been declared at the end of this report. Manjusha Rawat as well as our principal Mrs. Secondly I would also like to thank my parents and friends who helped me a lot in inalizing this project within the limited time frame. They are of two types: 1. Primary Cells 2. The chemical reaction in the cell is irreversible.

Daniel cell, Leclanche cell. SECONDARY CELL: It is that cell in which the electrical energy is first stored up as chemical energy and when the outside circuit is closed to draw the current from the cell the stored chemical energy is reconverted into electrical energy. The chemical reactions in this case are reversible. The two half cells are connected through a salt bridge. Here zinc acts as anode and copper acts as cathode.

At the anode, zinc undergoes oxidation to form zinc ions and electrons. The zinc ions pass into the solution. If the two electrodes are connected using an external wire, the electrons produced by the oxidation of zinc travel through the wire and enter into the copper cathode, where they reduce the copper ions present in the solution and form copper atoms that are deposited on the cathode.

The ions pass through the salt bridge to maintain charge balance until such a time as the anode and cathode reach electrical equilibrium of zero volts as chemical equilibrium is reached in the cell. The so-called "salt bridge" is not made of salt but could be made of material able to wick the cations and anions salts in the solutions, where the flow of positively charged cations along the "bridge" amounts to the same number of negative charges flowing in the opposite direction.

It is generally defined as the electrical potential for a source in a circuit. The internal resistance of a cell i. Is directly proportional to the distance between the electrodes. Is inversely proportional to facing surface area of the electrodes in electrolyte. Decrease with increase in temperature of electrolyte. Is inversely proportional to concentration of electrolyte. Draw the circuit diagram showing the scheme of connections.

The anode and the cathode are made from two different metals, or one metal and a film of carbon, and the electrolyte is an ionic liquid such as potassium hydroxide. When the cell is connected in a circuit chemical reaction start to take place at the anode and the cathode.

Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy. See our Privacy Policy and User Agreement for details. Published on Jan 20,. Comparing two different types of cell, as shown in this film, can make the practical more interesting, with potential for differentiation by ability. A simple fixed resistor would do, but make sure it can handle the maximum power you expect in the circuit — a few Watts.

Digital or analogue voltmeters or ammeters could be used instead of multimeters, but as Christina points out in the film, the use of multimeters is a skill your students will need to develop anyway. The electromotive force e or e. It is equal to the potential difference across the terminals of the cell when no current is flowing. In this equation V appears which is the terminal potential difference , measured in volts V. This is the potential difference across the terminals of the cell when current is flowing in the circuit, it is always less than the e.

When the internal resistance of the cell is decreased we can increase the potential difference across it , and hence make it more reliable.

A Potentiometer 2. A battery battery eliminator 3. Two way keys 4. A rheostat of low resistance 5. A galvanometer 6. A high resistance 7.

An ammeter 8. A cell 9. A set square Connecting wires Theory :- The internal resistance of a cell is the resistance offered by its electrolyte to the flow of ions. Draw the circuit diagram showing the scheme of connections. Clean the ends of the connecting wires with sand paper and make tight connections according to the circuit diagrams. Tight the plugs of the resistance box. Check the e.

Take maximum current from the battery , making rheostat resistance small. To test the corrections of the connections. Place the jokey first at the end P of the wire and then at the end Q. If the galvanometer shows deflection in opposite direction in the two cases the connections are correct. Without inserting the plug in the key K 2 adjust the rheostat so that a null point is obtained on the 4th wire of potentiometer. Insert the ohm plug back in the position in resistance box and by slightly adjusting the jockey near the previous obtained position of null point, obtain null point position accurately, using a set square.

Measure the balancing length l1 between the point and the end P of the wire. Take out the ohm plug again from the resistance box R. Slide the jockey along the potentiometer wire and obtain null point. Insert ohms plug back in its position in R.