Ohm’s law

Introduction

Ohm’s law shows the relationship between potential difference and electric current. If current flows through a conductor, the current is proportional to the voltage applied to the conductor. Ohm is the SI unit of electrical resistance. Famous German physicist Georg Simon Ohm worked on resistance in 1826 and published in 1827, in the book Die galvanische Kette, mathematisch bearbeitet. Ohm’s law was named in honour of the physicist Georg Simon Ohm. So, we will discuss what Ohm’s law is, application of Ohm’s law, limitations of Ohm’s law, Ohm’s law magic triangle, verification of Ohm’s law, water pipe analogy for Ohm’s law.

What is Ohm’s law?

Definition:

The voltage across any conductor is directly proportional to the current running through it, according to Ohm’s law. Supposing all the physical condition and temperature remains constant. 

Rho (Ω) is the SI unit of Ohm’s law. When the provided temperature and the other physical factors remain constant, then only this law is valid. Ohm’s law is invalid if the current rises the temperature in certain components. For example, in the filament of a light bulb, as the current increases, the temperature rises. In this condition, Ohm’s law will fail. Thus, the lightbulb filament violates  Ohm’s law. 

Equation of Ohm’s law

V  =  IR

Where V is the voltage across the conductor

I is the current flowing through the conductor 

R is the resistance of the conductor. 

You can calculate the current and resistance by the same formula.

I = V/R

R = V/I 

Ohm’s law magic triangle

Ohm’s law magic triangle is used to find the value of current, voltage, and resistance. Ohm’s law magic triangle makes it easy and interesting. It shows the relationship between current, voltage, and resistance in triangular form.

In Ohm’s law magic triangle, put the variable(V, I, R) in random order. When the two sides of a triangle are given, you can easily find the third side. For example, if the value of I and R is given and the value of V is asked, then, to calculate the value of V, simply put the V at the top and then put I and R on both sides. Then, multiply the value of I and R to get the value of V. In this way, you can also find the value of I and R.

V = I x R

Verification of Ohm’s law

For the verification of Ohm’s law

Apparatus required

• Resistor
• Ammeter
• Voltmeter
• Battery
• Plug key
• Rheostat

Theory: The voltage across any conductor is directly proportional to the current running through it, according to Ohm’s law. Supposing all the physical condition and temperature remains constant. 

Procedure:

1. In the first step, the key K is closed, and to get the minimum reading in Ammeter A and voltmeter V the rheostat Rh is adjusted.
2. In the circuit, the current is increased gradually by slowly moving the sliding terminal of the rheostat. The value of flowing current I in the circuit and the value of potential difference across the resistance wire is recorded during the process. So, the different values of voltage and current are recorded during the process.
3. Now, calculate the different values of voltage and current for each set in the ratio of V/I.
4. While calculating the value of V/I for each case, it will give a constant value of R, which is the resistance of the conductor.
5. Using the values, plot a graph between current and potential difference. It will be a straight line. You will know that the current is proportional to the potential difference.

Water pipe analogy for Ohm’s law

Water pipe analogy is a common analogy used to describe the current, voltage, and resistance. The amount of flowing water through the pipe is represented by the current, the voltage is represented by the water pressure, and the resistance is represented by the pipe size. Consider a water tank that has a hose attached to the bottom.

At the end of the hose, the pressure represents the voltage, The water of the tank represents the charge. The higher the level of water in the tank, the higher the charge. You can measure more pressure at the end of the hose.

 The current flows through a resistance, and when different voltages are applied at the end of the resistance, Ohm’s law describes this. The water pipe analogy helps you to understand electric circuits easily because you can’t see electrons. 

Applications of Ohm’s law

1. In an electric circuit, Ohm’s law determines the voltage, current, and resistance.
2. Ohm’s law is used to maintain the desired voltage drop across the electronic component.
3. Ohm’s law is used in DC shunts to divert the current and in DC ammeter.

Limitations of Ohm’s law

1. In some electrical elements like diodes and transistors, Ohm’s law is not applicable because these elements allow the current to flow in a single direction. 
2. There are some nonlinear electrical elements with parameters- capacitance, resistance, etc. Voltage and current will not be consistent throughout time, making Ohm’s law difficult to apply.

Conclusion

As we have discussed Ohm’s law, Ohm’s law magic triangle, verification of Ohm’s law, Ohm’s law water pipe analogy, application of Ohm’s law, and limitations of Ohm’s law. There are some other ways to understand Ohm’s law in a better way, and they are the Ohm’s law pie chart and Ohm’s law matrix table. All the different ways will explain how the voltage across any conductor is directly proportional to the current flowing through it. Ohm’s law governs the connection between current and voltage in an ideal conductor. But, Ohm’s law is not applicable everywhere. It has some limitations. It does not apply to semiconductors.