Statement, Formula, Solved Examples of Ohm’s Law

While many experiments are performed especially to show that some things are almost equal to the electric field, Ohm’s Law states that the electric current flowing from any conductor is directly proportional to the potential difference (voltage) between its terminals, assuming that the conductor’s physical condition does not change. In other words, the ratio of the potential difference between any two points of conductor to the current flow between them is constant, as long as the physical conditions (e.g., temperature, etc.) do not change. To better understand it, one should look at the given analogy for Ohm’s Law.

Definition

Voltage, current and resistance are the three fundamental components of electricity. Ohm’s Law illustrates the simple relationship between these three figures. It states that the voltage across the conductor is directly proportional to the current flowing in it, as long as all body conditions and temperatures remain constant. 

Formula

The rate at which one type of energy is converted to another type of energy Eg: mechanical energy, heat, magnetic fields or energy stored in electrical fields, is known as electrical power. Electrical power can be calculated using Ohm’s Law and by changing the values of current, voltage and resistance. The relationship between voltage or potential difference, current and resistance can be recorded differently. If two values are known, one can calculate the third unknown value using this Law. It is also very useful for electric formulas and calculators.

V = voltage, I = current and R = resistance

Voltage = Current × Resistance

V = I × R

Current = Voltage/Resistance

I = V/R

Resistance = Voltage/Current

R = V/I

Ohm’s Law Magic Triangle

The Ohm’s Law magic triangle is a visual representation of the mathematical relationship between voltage (V), resistance (R) and current (I). It is a simple tool to remember the three main electrical components.

Ohm’s law triangle consists of three phases: The upper part must be constant voltage. The lower half then divides into two smaller halves of current and resistance – the current is usually left, and resistance is right, but the order does not matter. Most people remember a formula like V = I × R and they write it in a triangle like that.

An Analogy for Ohm’s Law

Consider the matter of squeezing toothpaste as an analogy for Ohm’s Law. The compression force of the toothpaste is voltage, the small hole of the toothpaste resistance and the amount of toothpaste is current.

If one presses the toothbrush firmly, the toothpaste will come out well. Also, the smaller the hole, the less toothpaste will come out.

Another analogy for Ohm’s Law is the water and pipe model. We can model how the three variants relate if we have a water pump that uses a pressure (voltage) to push water near the current. If the water flow resistance remains the same and the pump pressure rises, the flow rate should increase. If the pressure remains the same and the resistance increases (making it more difficult for water to flow), the flow rate should decrease. If the flow rate remained the same while the flow resistance decreased, the required pressure from the pump would decrease.

Applications of Ohm’s Law

Some of the applications of Ohm’s Law include:

• Ohm’s Law is applied to the electrical circuit to determine the decrease in internal power in all electronic components.

• To calculate the unknown potential difference or voltage, resistance and power flow of an electrical circuit.

• Ohm’s Law applies to DC measuring circuits, especially to a DC ammeter where a low resistance shunt is used to divert current power.

• Electric heaters, kettles and other operating systems follow this Law.

Limitations of Ohm’s Law

Some of the limitations of Ohm’s Law are discussed below.

• Ohm’s Law does not apply to all non-metal drivers. For example, in silicon carbide, the relationship is given by V = KIm, where K and m are constants and m <1.

• Ohm’s Law applies to steel conductors in constant heat only. If the temperature changes, the Law does not apply.

• For non-linear electrical components with parameters such as volume, resistance to other electrical power and still will not always be constant in time makes it difficult to apply Ohm’s Law.

• Ohm’s Law also does not apply to integrated networks. Note that a network on one side contains compact elements such as transistors, diodes, etc. Combined elements are those elements that allow the flow of energy in only one direction.

Solved Example

A potential difference of 12 V is measured across 24 resistors. How much current flows through the resistor?

V = 12 V and R = 24 Ω, Current, I = ?

According to Ohm’s law, I = V/R = 12/24 = 0 .5 A

Conclusion

Ohm’s Law was probably the most important in the early descriptions of the value of electrical physics. Voltage, current and resistance are the three fundamental components of electricity. Ohm’s Law illustrates the simple relationship between these three figures. It states that the voltage across the conductor is directly proportional to the current flowing in it, as long as all body conditions and temperatures remain constant. The Ohm’s Law magic triangle is a visual representation of the mathematical relationship between voltage (V), resistance (R) and current (I).