Faculty of Engineering & Computing
Title of Experiment: Series and Parallel Circuits
Date Given: January 28, 2013
AIM: To investigate the circuits to tell whether the resistors are in parallel or in series also to determine the internal resistance of a 1.5V cell.
In this experiment it was expected of the experimenter to have a basic knowledge of circuits in both aspects theoretically and practically. A basic circuit comprises of a cell or power supply (some electric driving force) a load (some component that will use current) and connecting wires (these should be good conductors of electricity), as seen below.
Requirements of a circuit to function are it should be a closed circuit (a closed conducting path from negative to positive) also there has to be some potential difference as this causes the electrons to flow along the metal. This lab specifically investigates series circuits, parallel circuits and cells.
A series circuit has the same current flowing through all resistors adjacent to each other (in series), I=I1=I2…et cetera. The total potential difference (V) is equal to the sum of its individual potential differences, V=V1+V2. The individual potential differences are directly proportional to individual resistances, meaning each resistor in series has a corresponding voltage. The total resistance is equal to the sum of all resistances. A series circuit is shown below.
A parallel circuit on the other hand has the same potential difference across each resistor in parallel. The total current in a circuit is equal to the sum of individual currents. Individual currents are inversely proportional to individual resistances, meaning each resistor in parallel has a corresponding current value. The total effective resistance is less than the smallest resistor.
A cell is a single unit which provides electrical energy while a battery consists of multiple cells.
To investigate the circuits so as to determine whether they were series or parallel circuits and to determine the internal resistance of a 1.5V, cell the following were the objectives: To connect the circuit as shown in diagrams 1, 2 and 3 in the lab manual. To measure and record the current at points A, B and C in the diagrams and for activity #3 the current flowing through the resistor. To measure and record the total resistance of Activities 1 and 2. To measure and record the voltages across each of the resistors R1 and R2 and across R1 (point A) and R2 (point C) for activities 1 and 2. To measure and record the E.M.F. of the cell and the 100 Ω resistor. To analyse the data collected for Activities #1 and #2 to classify the circuit as series or parallel and if their values are consistent with that of the calculated value.
D.C. Power Supply (5V fixed)- To provide the voltage difference for the circuit necessary for the flow of electrons.
Bread Board- Used as a circuit board.
Digital Multimeter- Used to measure the voltage, current and resistance in the circuit.
R1- 15KΩ Carbon Resistor- Used to oppose current flow.
R2- 24KΩ Carbon Resistor- Used to oppose current flow.
R3- 100 Ω Carbn Resistor- Used to oppose current flow.
Alligator Clips- Used as connecting wires in the circuit.
1. In the lab the experimenter was required to set up the circuit based on the diagram. 2. The current at points A, B and C were measured using the digital multimeter and recorded for Activities 1 and 2. 3. The total resistance of the circuit was measured using the digital multimeter then recorded. 4. The voltages of each resistor were measured and recorded using the digital multimeter. 5. The voltage across both resistors (supply voltage) was measured and recorded using the digital multimeter. 6. Based on the results the experimenter identified whether the circuits were in series or in parallel. 7. In the 3rd activity the E.M.F. of the cell, the...
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