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Introduction
Ohm's Law, named after German physicist Georg Simon Ohm, is crucial in understanding electrical behavior in circuits within the realm of electrical engineering. Exploring this fundamental law reveals the mysteries of electrical phenomena for engineers, whether experienced or new to the field. Let's delve into the significance of Ohm's Law in engineering applications together.
Ohm’s Law
The relationship between voltage (V), the current (I) and resistance (R) in a d.c. circuit was first discovered by German scientist George Simon Ohm. This relationship is called Ohm’s law and may be stated as under:
The ratio of potential difference (V) between the ends of a conductor to the current (I) flowing between them is constant, provided the physical conditions (e.g. temperature etc.) do not change i.e.
`frac vi`= Constant = R
where R is the resistance of the conductor between the two points considered. For example, if in Fig. 1 (i), the voltage between points A and B is V volts and current flowing is I amperes, then V/I will be constant and equal to R, the resistance between points A and B. If the voltage is doubled up, the current will also be doubled up so that the ratio V/I remains constant. If we draw a graph between V and I, it will be a straight line passing through the origin as shown in Fig. 2 (ii). The resistance R between points A and B is given by slope of the graph i.e.
R=tan θ = V/I = Constant
Ohm’s law can be expressed in three forms viz.
I = V/R ; V = IR ; R = V/I
These formulae can be applied to any part of a d.c. circuit or to a complete circuit. It may be noted that if voltage is measured in volts and current in amperes, then resistance will be in ohms.
Figure 1
Figure 2
Ohm's Law is a fundamental tool for understanding and forecasting the performance of electrical circuits. It helps engineers establish the connection between voltage, current, and resistance, allowing for the enhancement of different electronic systems.
Non-ohmic Conductors
Those conductors which do not obey Ohm’s law (1 ∝ V) are called non-ohmic conductors e.g., vacuum tubes, transistors, electrolytes, etc. A non-ohmic conductor may have one or more of the following properties :
- The V-I graph is non-linear i.e. V/I is variable.
- The V-I graph may not pass through the origin as in case of an ohmic conductor.
- A non-ohmic conductor may conduct poorly or not at all when the p.d. is reversed.
The non-linear circuit problems are generally solved by graphical methods.
Figure 1
Figure 2
Figure 3
Above figure illustrates the graphs of non-ohmic conductors. Note that V-I graphs for these non-ohmic conductors are not a straight line.
Implications and Applications
The consequences of Ohm's law resound in many branches of electrical engineering, from simple circuit analysis to high-end electronics design.
- Circuit Design and Analysis: Ohm's Law acts as a foundation for building and studying electrical circuits. Engineers use it to determine the voltage, current, and resistance in different areas of a circuit which enables them to make the best component selection, ensure proper function, and solve circuit problems.
- Power Electronics: In power electronics applications like power supply design and motor control, Ohm's Law allows engineers to determine the suitable voltage and current ratings for components like resistors, capacitors and inductors. Using Ohm's Law, engineers assure the effective power delivery and minimal energy losses in electronic platforms.
- Electrical Safety: Having Ohm’s Law knowledge is critical for ensuring electrical safety in different setups such as homes, businesses, and industries. Engineers and electricians, using voltage, current, and resistance calculations in electrical circuits, can evaluate potential hazards, implement proper safety measures and prevent electrical incidents.
- Instrumentation and Measurement: Ohm's Law is the foundation of many electronic measurement techniques and instruments that include multimeters, oscilloscopes and signal generators. Engineers use Ohm's law for interpreting measurement data, for calibration of instruments, and for verification of electronic device performance.
Conclusion
Ohm's Law is essential in electrical engineering, offering a foundational structure for comprehending the operation of electrical circuits and parts. Engineers rely on the principles of Ohm's Law for tasks ranging from basic circuit analysis to advanced electronics design.