How Voltage, Current, and Resistance Relate to Ohm’s Law

The notion of Ohm’s Law underpins the fundamentals of electronics engineering. Current cannot flow in wires without Ohm’s Law, the voltage cannot exist without Ohm’s Law, and no circuit can function without Ohm’s Law. It’s just as significant in electronics as Newton’s Law is in physics. Of course, many other fundamental concepts and laws of electronics should be included. Still, we’ll focus on Ohm’s law equation, analysing simple circuits with Ohm’s Law and the Ohm’s law triangle technique, and how voltage, current, and resistance are connected to Ohm’s Law in this article.

What is Ohm’s Law?

Ohm’s Law is one of the most basic and crucial principles controlling electronic and electrical circuits. It links voltage, current and resistance for a linear device. Ohm’s Law is extremely significant since current, voltage, and resistance are the most important circuit parameters. In all electrical and electronic science disciplines, Ohm’s Law is applied. For example, it can calculate the value of resistors needed in circuits. It can also determine the amount of flowing current in a circuit where the voltage can be easily measured across a known resistor. Still, Ohm’s Law covers a wide range of calculations in all types of electronic and electrical circuits, wherever that current flows.

The current-voltage relationship is written as,

V=IR

Resistance is the constant of proportionality in the equation, with units of ohms and the symbol Ω.

Ohm’s Law is only valid if the temperature and other physical variables remain constant. Increasing the current in some components boosts the temperature. The filament of a light bulb, for example, increases in temperature when the current is raised. This situation cannot apply Ohm’s Law. The lightbulb filament breaks Ohm’s Law.

The voltage across a conductor is precisely proportional to the current flowing through it, provided all physical parameters and temperature stay constant, according to Ohm’s Law.

Ohm’s law equation

V = IR, where V is the voltage across the conductor, I is the current flowing through the conductor, and R is the resistance to current flow provided by the conductor.

Ohm’s Law Triangle Technique

Ohm’s Law is a straightforward and practical technique for studying electric circuits. It is so commonly used in the study of electricity and electronics. To begin, make a triangle with the letters E, I, and R. If you know E and I and want to figure out R, take R out of the equation and observe what’s left. If you know E and R and want to figure it out, leave I out and see what’s left. Finally, if you know I and R and want to figure out E, take out E and see what’s left. You’ll eventually need to be comfortable with algebra to study electricity and electronics truly, but this technique can help you remember your first calculations. If you’re familiar with algebra, you must memorise E=IR and use it to derive the other two formulas when you need them.

How to Analyse Simple Circuits with Ohm’s Law

Resistive circuits can use Ohm’s Law. The Ohm’s Law Equations required for the analysis are basic but must pair them with the correct notions to comprehend Ohm’s Law. Ohm’s Law is frequently used in classrooms and calculations in-field to determine a circuit’s voltage, current, and resistance. The Law states that V = I * R, where V represents voltage, I represents current, and R represents resistance. Using this Law, you can compute an ideal resistive circuit’s voltage, current, and resistance.

Method 1: 

Analysing simple Circuits with Ohm’s Law

Determine if the circuit has to be wired parallel or in series. In only one path, the current flows when a circuit is linked in series – when parallelly wired, the current can flow over many routes side-by-side. Two of these sorts of circuits can behave extremely differently, and it’s crucial to know which one you’re dealing with. Next, determine the circuit’s voltage. Ohm’s Law can be used to compute voltage in resistive circuits. To perform this calculation, you’ll have to know the circuit’s current and resistance values. Then, the circuit’s voltage can be calculated by multiplying these quantities together.

Consider a circuit with a current of three amps (I = 3A) and a resistance of two ohms (R = 2 ohms). Then, the following equation can be used to calculate the voltage (V) for this circuit:

V= I * R

V=3A * 2 ohms

V=6 volts

Calculate the circuit’s current. 

It is found by analysing simple circuits with Ohm’s Law. To perform this calculation, you’ll have to know the circuit’s voltage and resistance values. The voltage has to be divided by the resistance to find the circuit’s current.

Take a circuit of 6 volts of voltage(V = 6V) and 2 ohms resistance (R = 2 ohms). Then, the following equation can be used to calculate the current (I) in this circuit:

V= I * R

V/I = R

1/I= R/V

I = V/R

I = (6 V) /(2 ohms)

I= 3A

Calculate the circuit’s resistance. 

You can use Ohm’s Law to calculate the resistance of a resistive circuit. To calculate the resistance, you’ll need to know the circuit’s voltage and current numbers. When these values are known, divide the circuit’s voltage by the current to find the resistance. For example, take a circuit with a voltage of 6 volts (V = 6V) and a resistance of 2 ohms (R = 2 ohms). Then, the following Ohm’s law equation can be used to calculate the current (I) in this circuit:

V = I * R

V/R = I

1/R = I/V

R = V/I

R= (6V)/ (3A)

R=2 ohms

Understand the “Table Method”.

“The table technique is a great approach to figure out how much resistance different resistors in a circuit have. Make a table with three rows and a column for each circuit’s resistors, plus one for the overall circuit. For example, if you have a circuit with three resistors, you will build a table with three rows and four columns. The voltage across each resistor will be represented by the first row, the current through each resistor by the second row, and the resistance of each resistor by the third row. The voltage across all resistors is equal to the overall circuit voltage for parallel circuits. It means that all of the numbers in Row 1 will be identical. The overall circuit current is equal to the sum of all resistor currents. The sum of all the other columns in Row 2 will equal the final column in Row 2. As more resistors are added, the total resistance decreases. The last column in Row 3 will be obtained using the equation: 1 / ((1/R1) + (1/R2)… + (1/Rn-1) + (1/Rn) for a circuit with “n” resistors.

Method 2:

Knowing the Variables of Ohm’s Law

Consider the difference between pressure and voltage. 

Voltage is defined as the charge difference between two points. It is measured in volts, abbreviated as “V.” A full tank of water and an empty tank connected by a hose is a common visual representation. Water pressure is high in the full tank and low in the empty tank. A differential in water pressure is analogous to a charge difference between two circuit terminals.

The flow of charge is known as current. Current exists due to the presence of charge difference between one point and the other. It is the charge movement from a place of high charge to the low charge point, and the measurement takes place in amperes and is denoted by the letter “A.” A suitable analogy is a line connecting a full water tank to a tank which remains empty. Water flows from a full tank (high pressure) to a tank which remains empty (low pressure), just as current moves from a high charge (source) to a low charge (destination) (ground).

Consider the material’s ability to withstand current.

The substance through which current flows has a property called resistance. It varies depending on the material and is measured in Ohms, abbreviated “ohms.” The degree to which a material prevents current from flowing through it is its resistance. High resistance obstructs current more, while low resistance obstructs less current.

Method 3

Knowing the Components of a Resistive Circuit

Identify your power source. 

There must be a charge difference before the current flows via a circuit. The positive side of a power source is referred to as the positive side, while the negative side is referred to as the negative side. The positive and negative sides are connected via a circuit. When extra elements are added to the circuit to transform the flowing current into usable work, electricity is harnessed.

Understand the meaning of nodes.

The intersections between distinct parts of a circuit are known as nodes. The nodes in a typical circuit are the wires that connect the various circuit sections. Things that are connected in parallel have more nodes than things that are connected in series.

Define a resistor. 

A resistor is a current-limiting electrical component. Resistors do not produce electricity, but they do consume it. They also provide a fixed amount of resistance, which does not alter.

Know that no other components are present. 

The source, resistor(s), and nodes are the only components present in a perfect resistive circuit (or wires). No other components, such as capacitors, are present in an ideal resistive circuit. Current flow according to the principles of Ohm’s Law in these ideal circuits: V=I*R.

Conclusion

Ohm’s Law equation is mostly used to determine an electric circuit’s voltage, resistance, and current. Ohm’s Law is applied to keep the voltage drop to the desired level across the electronic components. In the case of electrical elements like diodes and transistors, which allow current to flow in one direction only, Ohm’s Law does not apply. In addition, voltage and current will not be constant concerning time for nonlinear electrical elements with factors like capacitance, resistance, and so on, making Ohm’s Law difficult to apply.