Experiment using Ohm's law, Lab Reports of Electrical Circuit Analysis

Download Experiment using Ohm's law and more Lab Reports Electrical Circuit Analysis in PDF only on Docsity! EXPERIMENT NO.3-M OHM’S LAW OBJECTIVES: 1. To be familiar with Ohm’s Law. 2. To study the sign conversions as regard to voltage and current. DISCUSSION: For most materials and under fixed environmental conditions, the current in its directly proportional to the potential difference across it. The proportionality constant is the resistance of the material. This relationship is known as Ohm’s Law. In equation form, we write V=IR Ohm’s Law is applicable whether we are dealing with simple circuit or with parts of a more complex circuit. The resistance used in the equation could be that of a single resistor or the equivalent resistance of a group of resistors. In using Ohm’s law, we should be consistent as regard the quantities used in the equation. A current Iab is positive if it is directed from the point a to a point b. we could easily establish this direction by using an ammeter. A conventional ammeter would have an uphill deflection if the current enters its positive terminal and leaves its negative terminal. A potential difference Vab is positive if point a is at a higher potential than point b. again, this could be easily be establish using a voltmeter. A conventional voltmeter will have an uphill deflection if its positive terminal is maintained at a higher potential. INSTRUMENT AND COMPONENTS: VOM DC Voltmeter DC Ammeter 250 ohm resistor 100 ohm resistor 75 ohm resistor 50 ohm resistor DC Power Supply Connecting Wires PROCEDURE: 1. Connect the circuit shown in Fig 3.1. Set the DC power supply at 20V. 2. Measure and record Iab. Since this is the total current supplied by the power supply, the equivalent resistance between points a and e is equal to E/Iab. 3. Disconnect the supply voltage and measure the resistance between a and e using VOM. Compute the percent difference between the two values. 4. Place the supply back. Measure and record the voltage and current indicated in the table. EXPERIMENTAL CIRCUIT DIAGRAM: R, R, 3 AW b WW 7 Rs — . =F a = Ry © PROBLEMS: 1. Why Ohm’s law can’t be described in terms of constant proportionality? Because the Ohm's law is made up of I=V/R, each of which has its own set of features and value. 2. Why does the E/I ratio of an electric circuit indicate its ability to oppose electric current rather than its ability to permit current flow? Because the E/I is made up of numerous resistors linked in series and parallel, rather than a single resistor that may allow or prevent electron passage depending on the current flowing through it. 3. An electric fuse consists of a small strip of wire with a low melting temperature. The current in the protected circuit flows this strip. Which will have a greater resistance, 10A fuse or a 20A fuse? Explain. The resistance of the 20A will rise according to Ohm's law, which states that R=IV, which implies that as the current increases, so too will the resistance. 4. If a voltage is doubled and resistance is halved in a circuit, what is the relationship of the new current to the original current? Explain The number one law in circuit analysis is Ohm’s law: V = IR. Under this relationship, if voltage doubles and resistance halves, you will get 4x the original current. CONCLUSION The strength of a direct current is directly proportional to the potential difference and inversely proportional to the resistance of the circuit. Just be careful when doing the experiment, and it is much easier to read when it’s in digital.