What Is Ohm’s Law? Definition, Formulas, and Examples

What is Ohm’s Law? – Basically, in a closed circuit there will be a flow of electric current. Where the electric current flows because of a potential difference between two points in an introduction, for example on a flashlight, television, radio, and others. The equipment can turn on or function if there is electricity that comes from the voltage connected to the equipment itself. So it will produce a potential difference.

Ohm’s law is one of the basic sciences of electronics. This one science is very useful to help us in calculating the current, voltage, or resistance of an electric circuit. Where ohm’s law states the relationship between mathematical and current, voltage, and also network resistance. The name of the law is taken from a German physicist and mathematician named Georg Simon Ohm. Ohm was the first to examine the relationship between electric current strength and potential difference in a conductor. In that research, Ohm found a mathematical relationship between electric current strength and potential difference, which eventually became known as Ohm’s Law.

It is known that the greater the potential difference that appears, the greater the current flowing. The magnitude of the ratio between the potential difference and the electric current strength is always the same or constant. So that the potential difference is equivalent to the current strength (V ~ I). When viewed mathematically, it can be written that V = mxl, m is a constant ratio between the potential difference and the current strength.

One of the formulas that describes Ohm’s Law is that it reads, “the current flowing in a conductor is proportional to the potential difference that exists between the ends of the conductor provided that the temperature is constant or constant.

In everyday life, sometimes we will find an electrical device that reads 220 V/2 A. This writing was not written without a purpose. Where the purpose of this article is to inform that the electric device will work optimally and for a long time if it is installed with a voltage of 220 V and a current of 2 A. Then, what if it is installed at a higher or lower voltage? For example, if there are two lamps that say 220 V/2 A, they are installed at 440 V and 55 V. So what will happen?

For lamps that are installed at a higher voltage, it will result in the lamp shining brighter but not lasting long. Meanwhile, for lights that are installed at a lower current voltage, it will cause the lights to become dim. Therefore, you should always pay attention to the instructions for using power tools.

Understanding Ohm’s Law

According to Wikipedia, Ohm’s Law is an electric current which is proportional to voltage and inversely proportional to resistance. Meanwhile, according to Collins Dictionary, Ohm’s Law is the principle of an electric current flowing through a conductor that is proportional to the potential difference. However, the temperature remains constant. The proportional constant is the resistance of the conductor.

Ohm’s Law equations and Ohm’s Law formulas describe how current flows through any material when a voltage is applied. One thing you need to remember is the difference between low resistance and high resistance. An electric cable or other conductor has low resistance, meaning that current will flow easily. Conversely, if the resistance is high, the current will be difficult to flow.

Understanding Ohm’s Law above will not help much if we don’t know what variables we use, what are the equations, and how to use them. If based on the American English Dictionary, Ohm’s Law has a ratio that is proportional to the current in the dc circuit given the voltage and inversely proportional to the resistance. Not only dc, Ohm’s Law also applies to ac circuits.

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Ohm’s law is usually described by graphing the linear relationship between voltage (V) and current (I) in an electric circuit. We can imagine how Ohm’s Law looks like with a pipe illustration.

a. The water pipe is the resistance (R) in the circuit, calculated in Ohms (Ω).
b. Water is an electric current (I) flowing in a circuit, calculated in amperes (A).
c. The difference in height between the water is the voltage (V) in the circuit, calculated in volts (V).

From the explanation above, the illustration goes like this:

a. If the water pipe is narrow or the resistance is high, this will limit the water or electric current flowing in the circuit.
b. If the water pipes are wide or have low resistance, this will increase the water or electric current flowing in the circuit.

Ohm’s Law sounds

At first, Ohm’s Law consisted of two parts. The first part is the definition of resistance, namely V = IR. This relationship is often called Ohm’s Law. However, Ohm also said that R is a constant that does not depend on V or I. The relationship V =IR can be applied in any resistor, where V is the potential difference between the two ends of the resistance and I is the current flowing through it. While R is the resistance or resistance of the resistor.

Ohm’s law itself reads, “The strength of the current flowing in a conductor or resistance is proportional to the potential difference or voltage between the ends of the conductor. The statement can be written as follows, namely I ∞ V.”

In everyday life, current strength is needed like electric current strength. For example, when connecting a wire to a 6 V battery, the current flow will be doubled compared to when connecting to a 3 V battery.

From here, let’s say we take an example of electric current with the flow of water in a pipe or river which is affected by gravity. If the pipe and river are almost flat, the water velocity will be relatively small. However, if one end is higher than the other, then the flow velocity or current will be greater. The greater the difference in height, the greater the current. That said, the amount of current flowing in the wire does not only depend on the voltage. But it also depends on the resistance provided by the wire to the flow of electrons. Pipe walls or river banks and also the rocks in the middle, can provide obstacles to the flow of currents. In the same way, electrons will be slowed down due to interactions with the atoms of the wire. The higher the resistance, the smaller the current in a voltage V.

Electrical resistance

According to Ohm’s Law equation, electrical resistance can be interpreted as the quotient of the potential difference between the ends of the conductor and the current flowing in the conductor itself. To commemorate the services of Georg Simon Ohm, his name is used as a unit of electrical resistance that we know as Ohm or (Ω) or the conductor is said to have a resistance of one ohm if an electric current of one ampere flows in the conductor. Where it is due to the potential difference between the ends of the conductor of one volt.

Types of Barriers

In everyday life, there are several types of resistance or resistors that are often used according to their needs. The types of obstacles are as follows:

a. Fixed Resistors

In fixed resistors which are generally made of carbon or thin nichrome wire, the value of the resistance is symbolized by various colors that circle on the outer shell. The color symbol has a meaning according to its location.

b. Variable Resistors

There are two types of variable resistors that we know on the market, namely rotating and shifting type variable resistors. Basically, the way the two resistors work is the same, namely by shifting or rotating the sliding contacts to increase or decrease the resistance value as needed. We can find these variable resistors in the volume system on radios, tape recorders, and other electronic equipment.

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Measuring Barriers

From the explanation above, we already know how to measure the amount of current or potential difference in a conductor. Now, we will discuss how to measure the amount of electrical resistance. Where to measure electrical resistance there are two ways that we can use, namely directly and indirectly.

a. Measuring Barriers Directly

Most people must have known a multimeter, which is a tool that can be used to measure current strength, potential difference, and resistance. To measure resistance using a multimeter, we must first turn the switch inside the multimeter in the direction marked R. That way, the multimeter already functions as an ohm meter or resistance meter. Connect the ends of the multimeter terminals with the ends of the objects whose resistance will be measured. Then pay attention to the scale displayed on the multimeter.

b. Measuring Barriers Indirectly

Apart from using a multimeter, we can also combine voltmeters and ammeters together in the electrical circuit where the resistance will be measured. The voltmeter is connected in parallel, while the ammeter is connected in series with the object whose resistance is to be measured.

c. Barriers to the Conducting Wire

The conductor wire used in electric wire will certainly have resistance, even though the value is small. To determine the factors that affect the amount of resistance of a conductor.

Ohm’s Law formula

Mathematically, Ohm’s Law formula is V = I x R. Where I is the electric current flowing in a conductor in units of amperes. While V is the electric voltage at both ends of the conductor in units of volts. Then R is the value of the electrical resistance or resistance in a conductor in units of Ohms. The relationship between electric current, resistance, and voltage in a circuit is in Ohm’s Law.

When making experiments on electricity, Ohm found the following things:

a. If the resistance is constant, the current in each circuit is directly proportional to the voltage. But if the voltage increases, the current will also increase and if the voltage decreases, the current will also decrease.
b. If the voltage remains constant, then the current in the circuit becomes inversely proportional to the circuit. But if the resistance increases, the current will decrease and if the resistance decreases, the current will increase.

In a constant resistance, the current as well as the voltage will vary.

Ohm’s law itself can be expressed in the form of a formula. Where the basic formula is stated as follows.

R = the amount of electrical resistance
I = the amount of electric current flowing
E = the amount of electric voltage that is in a closed circuit

Ohm’s Law circuit

Below are several circuits in calculating Ohm’s Law, including:

a. How to Calculate Series Resistors

In a series of resistors arranged in series, the total resistor value can be obtained by adding up all the resistors arranged in series. This refers to the notion that the current strength at all points in a series circuit will always be the same.

b. How to Calculate Parallel Resistors

In a series of resistors arranged in parallel, the calculation of the total resistor value refers to the understanding that the magnitude of the current entering the branch is equal to the magnitude of the current coming out of the branch.

c. How to Calculate Series Capacitors

In a series of capacitors arranged in series, the total capacitor value is obtained by the calculation above.

d. How to Calculate Parallel Capacitors

In a series of several capacitors arranged in parallel, the total capacitor value is the sum of all the values ​​of the capacitors arranged in parallel.

Example of Ohm’s Law Problem

Three resistors are arranged in series, each value is 4 ohms, 3 ohms and 5 ohms. This resistance is then installed at 120 volts. Calculate the magnitude of the voltage across the 3 ohm resistance.

Answer:
R1 = 4 ohms
R2 =3 ohms
R3 = 5 ohms
V = 120 volts

Rtotal = 4 ohms + 3 ohms + 5 ohms = 12 ohms
V = I . R
I = V/Rtotal = 120 /12 = 10 A
V on R2 (rated 3 ohms) is
VR2 = IX R2
= 10 X 3
= 30 volts

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