Zhikai Basic Circuits - Basic Circuits Wang Zhikai Group B6...

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Basic Circuits Wang Zhikai Group B6 Pc1222 Lab Report: Basic Circuits 1 Objective Investigate the relationship among three variables (resistance, current and voltage) in direct current circuits. Investigate the circuit characteristics of resistors in series and parallel arrangements. 2 Introduction When a voltage or potential difference (∆V) is applied across a material, the current (I) through the material is found to be proportional to the voltage, I α ∆V . The resistance (R) of the material is defined as the ratio of the applied voltage and the resulting current, or in equation format, R = . For many materials, the resistance is constant, or at least approximately so, over a range of voltages. A material with constant resistance is said to obey Ohm’s law. The unit for resistance is voltage/amphere (V/A), also known as the ohm (Ω). In any electrical circuit, Ohm’s law may be applied to either the entire circuit or to an isolated segment of the circuit. If Ohm’s law is applied to the entire circuit, V refers to the terminal input voltage supplied by the battery, which acts as a source for the voltage, while R is the total resistance of the circuit. When Ohm’s law is applied to an isolated segment of the circuit, V, R and I are the individual voltages, resistances and currents for that segment. The purpose of this experiment is to investigate Ohm’s law by measuring the voltages, currents and resistance of a circuit in series, parallel, and combination of the two. We can then determine if our experimental results deviates from the results predicted by the theoretical relationship of Ohm’s law. We will then be able to analyse the factors that caused the deviation, if any. 3 Methodology Part A: Ohm’s Law and Resistances Our purpose is to investigate the 3 variables (resistance, voltage and current) involved in a mathematical relationship called Ohm’s Law. We connected each resistor to the circuit on the circuit board and measured the current and voltage across the resistor. We then made 10 independent measurements of 10 different resistors using the digital multimeter (DMM). Part B: Series Circuit Our purpose is to investigate the current-voltage relationships for resistances in a series circuit. We measured the resistance of three unequal resistors using the DDM. Next, we set up the three resistors in series using the PASCO circuit experiment board and measured both the total voltage/current/resistance as well as the voltage/current/resistance for each individual resistor. The current is measured by interrupting the circuit in between resistors with the DDM. Part C: Parallel Circuit Our purpose is to investigate the current-voltage relationships for resistances in a parallel circuit. We measured the resistance of three unequal resistors using the DDM. Next, we set up the three
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Zhikai Basic Circuits - Basic Circuits Wang Zhikai Group B6...

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