What is OHM'S LAW? ➡️ Learn it EASY With Exercises

Introduction to Ohm's Law:

Ohm's law It is the starting point for understanding the basic fundamentals of electricity. From this point of view it is important to analyze the statement of Ohm's Law in a practical theoretical way. Due to our experience in the field, the analysis of this law allows us to even make the dream of any specialized personnel in the area come true: work less and perform more, since with a correct interpretation we can detect and analyze electrical faults. Throughout this article we will talk about its importance, origin, use of applications and secret to better understand it.

¿Who discovered Ohm's law?

Georg simon ohm (Erlangen, Bavaria; March 16, 1789-Munich, July 6, 1854) was a German physicist and mathematician who contributed Ohm's law to the theory of electricity. [1]. Ohm is known for studying and interpreting the relationship between the intensity of an electric current, its electromotive force and resistance, formulating in 1827 the law that bears his name that states that I = V / R. The unit of electrical resistance, the ohm, is named after him. [1] (see figure 1)

Georg Simon Ohm and his Ohm's Law (citeia.com) — Figure 1 Georg Simon Ohm and his Ohm's law (https://citeia.com)

What does Ohm's law state?

La Ohm's law establishes: The intensity of current that passes through an electrical circuit is directly proportional to the voltage or voltage (potential difference V) and inversely proportional to the electrical resistance it presents (see figure 2)

Understanding that:

Quantity	Ohm's law symbol	Unit of measure	Role	In case you're wondering:
Tension	E	Volt (V)	Pressure that causes the flow of electrons	E = electromotive force or induced voltage
Current	I	Ampere (A)	Electric current intensity	I = intensity
Resistance	R	Ohm (Ω)	flow inhibitor	Ω = Greek letter omega

E= Electric Potential Difference or electromotive force “old school term” (Volts “V”).
I= Intensity of electric current (Amperes “Amp.”)
R= Electrical Resistance (Ohms “Ω”)

Figure 2; Ohm's Law Formula (https://citeia.com)

What is Ohm's law for?

This is one of the most interesting questions that electricity / electronics students of the first levels ask themselves, where we suggest that you understand it very well before continuing or advancing with another topic. Let's analyze it step by step: Electric resistance: It is the opposition to the flow of electric current through a conductor. Electric current: It is the flow of electric charge (electrons) that runs through a conductor or material. The current flow is the amount of charge per unit of time, its unit of measurement being the Ampere (Amp). Electric potential difference: It is a physical quantity that quantifies the difference in electric potential between two points. It can also be defined as the work per unit charge exerted by the electric field on a charged particle to move it between two determined positions. Its unit of measurement is the Volt (V).

Conclusion

Ohm's law It is the most important tool for the study of electrical circuits and a fundamental basis for studies of Electricity and Electronics careers at all levels. Devoting time to its analysis, in this case developed in this article (at its extremes), is essential to understand and analyze the secrets for troubleshooting.

Where we can conclude according to the analysis of Ohm's Law:

The higher the potential difference (V) and the lower the resistance (Ω): The greater the intensity of electric current (Amp).
A lower potential difference (V) and higher resistance (Ω) : Less electric current intensity (Amp).

Exercises to understand and put Ohm's Law into practice

1 Exercise
2 Exercise
3 Exercise
4 Exercise
5 Exercise

1 Exercise

Applying the Ohm's law In the following circuit (figure 3) with a resistance R1= 10 Ω and potential difference E1= 12V applying Ohm's law, the result is: I=E1/R1 I= 12V/10 Ω I = 1.2 Amp.

Figure 3 Basic electrical circuit (https://citeia.com)

Ohm's Law Analysis (Example 1)

To analyze Ohm's law we are going to virtually move to the Kerepakupai Merú or Angel Falls (Kerepakupai Merú in the Pemón aboriginal language, which means "jump from the deepest place"), it is the highest waterfall in the world, with a height of 979 m (807 m of uninterrupted fall), originated in the Auyantepuy. It is located in the Canaima National Park, Bolívar, Venezuela [2]. (see figure 4)

comparison of angel leap and Ohm's law — Figure 4. Analyzing Ohm's Law (https://citeia.com)

If we imaginatively carry out an analysis applying the Ohm's law, making the following assumptions:

Cascade height as the potential difference.
Water obstacles in the fall as resistance.
The Water Flow Rate of the Cascade as the Electric Current Intensity

Exercise 2:

In a virtual equivalent we estimate a circuit for example from figure 5:

Ohm's law analysis — Figure 5 Analysis of the lay of Ohm 1 (https://citeia.com)

Where E1= 979V and R1=100 Ω I=E1/R1 I= 979V/100 Ω I= 9.79 Amp.

citeia.com

Ohm's Law Analysis (Example 2)

Now in this virtualization, for example, if we move to another waterfall for example: Iguazú Falls, on the border between Brazil and Argentina, in Guaraní Iguazú means "big water", and it is the name that the native inhabitants of the Southern Cone of America gave the river that feeds the largest waterfalls in Latin America, one of the wonders of the world. However, in recent summers they have had problems with the water flow.[3] (see figure 6)

virtual comparison Iguazu Falls with ohm's law — Figure 6 Analyzing Ohm's Law (https://citeia.com)

Exercise 3:

Where we assume this virtual analysis is E1 = 100V and R1 = 1000 Ω (see figure 7) I = E1 / R1 I = 100V / 1000 Ω I = 0.1 Amp.

Ohm's law analysis 2 — Figure 7 Analysis of Ohm's law 2 (https://citeia.com)

Ohm's Law Analysis (Example 3)

For this example, some of our readers may ask, and what is the analysis if the environmental conditions in the Iguazú waterfall improve (which we hope will be the case, remembering that everything in nature must have a balance). In the virtual analysis, we assume that the ground resistance (to the passage of the flow) in theory is a constant, E would be the accumulated upstream potential difference where as a consequence we will have more flow or in our comparison current intensity (I), would be for example: (see figure 8)

comparing Iguazú waterfall and Ohm's lay — figure 8 analysis of Ohm's law 3 (https://citeia.com)

citeia.com

Exercise 4:

By Ohm's law, if we increase the potential difference or accumulate its electromotive force higher, keeping the resistance constant E1 = 700V and R1 = 1000 Ω (see figure 9)

I = E1 / R1
I = 700V / 1000 Ω
I = 0.7 Amp

We observe that the current intensity (Amp) in the circuit increases.

electrical circuit — Figure 9 analysis of Ohm's law 4 (https://citeia.com)

Analyzing Ohm's Law to understand its secrets

When one begins to study Ohm's law, many wonder how such a relatively simple law can have any secrets? Actually there is no secret if we analyze it in detail in its extremes. In other words, not analyzing the law correctly can, for example, cause us to disassemble an electrical circuit (whether in practice, in an appliance, even at an industrial level) when it can only be a damaged cable or connector. We are going to analyze case by case:

Case 1 (Open circuit):

analysis of an open electrical circuit — Figure 10 Open electrical circuit (https://citeia.com)

If we analyze the circuit in figure 10, by Ohm's law the power supply E1 = 10V and the resistance in this case is an insulator (air) that tends to be infinite ∞. So we have:

I = E1 / R
I = 10V / ∞ Ω

Where the current tends to be 0 Amp.

Case 2 (Circuit shorted):

analysis of a shorted electrical circuit — Figure 11 Electrical circuit in short circuit (https://citeia.com)

In this case (figure 11) the power supply is E=10V, but the resistor is a conductor that in theory has 0Ω, so in this case it would be a short circuit.

I = E1 / R
I = 10V / 0 Ω

Where the current in theory tends to be infinite (∞) Amp. What would trip the protection systems (fuses), even in our simulation software triggered the caution and fault alarms. Although in reality modern batteries have a protection system and current limiter, we recommend our readers to check the connections and avoid short circuits (batteries, if their protection system fails, can explode "Caution").

Case 3 (connection or wiring failures)

If we fear in an electrical circuit a power source E1 = 10V and an R1 = 10 Ω we must have by Ohm's law;

Exercise 5:

I = E1 / R1
I = 10V / 10 Ω
I = 1 Amp

Now we assume that in the circuit we have a fault due to a wire (internally broken or broken wire) or bad connection, for example, figure 12.

broken wire fault circuit — Figure 12 Circuit with Internally Split Wire Fault (https://citeia.com)

As we have already analyzed with an open resistor, the damaged or broken conductor will have a similar behavior. The intensity of electric current = 0 Amp. But if I ask you which section (figure 13) is A or B damaged? and how would they determine it?

Broken or broken wire circuit analysis — Figure 13 Circuit analysis with damaged or internally broken cable (https://citeia.com)

Surely your answer would be, let's measure continuity and simply detect which of the cables is damaged (so we have to disconnect the components and turn off the E1 power supply), but for this analysis we are going to assume that the source cannot even be turned off or disconnect any wiring, now the analysis gets more interesting? One option is to place a voltmeter in parallel to the circuit as for example figure 14

Faulty Circuit Analysis Using Ohm's Law — Figure 14 Faulty Circuit Analysis (https://citeia.com)

If the source is operational, the voltmeter should mark the default Voltage in this case 10V.

Analyzing electrical circuit faults with Ohm's law — Figure 15 Faulty Circuit Analysis by Ohm's Law (https://citeia.com)

If we place the voltmeter in parallel to Resistor R1, the voltage is 0V if we analyze it by Ohm's law we have:

VR1 = I x R1
Where I = 0 Amp
We fear VR1 = 0 Amp x 10 Ω = 0V

Figure 16 analyzing wiring fault by Ohm's law (https://citeia.com)

Now if we place the voltmeter in parallel to the damaged wire we will have the voltage of the power supply, why?

Since I = 0 Amp, the resistance R1 (has no opposition from the electric current creating a virtual earth) as we already analyzed VR1 = 0V So we have in the damaged cable (in this case) the Voltage of the power supply.

V (damaged wire) = E1 - VR1
V (damaged wire) = 10 V - 0 V = 10V

I invite you to leave your comments and doubts that we will surely answer. It can also help you to detect electrical faults in our article on Electrical measuring instruments (Ohmmeter, Voltmeter, Ammeter)

It can serve you:

References:[1] [2] [3]

Ohm's Law and its secrets [STATEMENT]