Experiment No.2 Ohm's law for linear and nonlinear circuit, Study notes of Law

Download Experiment No.2 Ohm's law for linear and nonlinear circuit and more Study notes Law in PDF only on Docsity! University of Anbar College of Engineering Dept. of Electrical Engineering Lab. Name: :fundamental of Electric circuit Experiment no.: Lab. Supervisor: 1 Experiment No.2 Object To study the relation between voltages and currents for linear elements. Theory In any electric circuit, the larger charge flows(current), the large amount of amount of energy converted to heat. This characteristic behavior of materials is referred to as the resistance of the material to the flow of electrical charge. The symbol for a resistor is shown in Fig.1 Fig.1 Ohm's law describes the relationship between the terminal voltage and current of a resistor, and stated as follows: - The ratio of potential difference (V) between any tow points on a conductor to the current (I) flowing between them is constant, if the temperature of the conductor dose not change in the words: R=V/I  V: is the potential difference and measured in volt (V).  I: is the current flowing through the conductor and measured in Ampere(A).  R: is the resistance of the conductor and measured in Ohm(Ω). Ohm's Law for Linear Elements The Fig.2 shows the linear (straight-line) graph between the voltage drop and the current flow through affixed resistance (R=20 Ω) & (R=40 Ω). Ohm's law for linear and nonlinear circuit University of Anbar College of Engineering Dept. of Electrical Engineering Lab. Name: :fundamental of Electric circuit Experiment no.: Lab. Supervisor: 2 Fig.2  Non-linear resistance: the incandescent lamp The V/I characteristic of Fig.2 is that of a so-called perfect resistor, an ideal device which keeps a constant and unaltered resistance in all physical conditions. In practice all materials have a V/I charstristics which is intrinsically non-linear and dependent on parameters such as temperature, mechanical stress, age, etc.… In most case it is desirable that the resisters used in electronics have values which are as constant as possible, and therefore these components are mode out of materials selected for this purpose. In certain other cases a non-linear V/I catachrestic may turn out useful for specific purposes. We shall examine some of these devices, starting, from a common incandescent lamp, which allows us understand the meaning of non-linear I/V charstristics. Set up the equipment's as shown in Fig.3 University of Anbar College of Engineering Dept. of Electrical Engineering Lab. Name: :fundamental of Electric circuit Experiment no.: Lab. Supervisor: 5 6 8 10 Table 1.a 3. For non-Linear resistance. Power supply (volt) I measured (mA) R calculated (Ω) 0 2 4 6 8 10 Table 1.b Discussion 1. Plot a graph from the measured data of table.1, to show the relationship between V & I. 2. Calculate the slope and resistance value from the graph above. 3. From the graph above, is the relationship between V&I linear or non- linear? 4. From the result shown in Fig.6, find the resistance and slope value University of Anbar College of Engineering Dept. of Electrical Engineering Lab. Name: :fundamental of Electric circuit Experiment no.: Lab. Supervisor: 6 Fig.6 5. Can you tell me, what is the difference between number (2) and number (4)?