What is the Ohm’s Law?

Ohm’s Law states that the current flowing through a conductor is directly related to the potential difference across its ends when all physical conditions such as the temperature of the conductor remain constant.

Basically, Ohm’s Law is the measure of Resistance in an electrical circuit by measuring Voltage and Electrical Current in the circuit. So, Ohm’s Law is a formula that shows how voltage, current, and resistance work together in an electrical circuit.

History of Ohm’s Law by Georg Simon Ohm

Georg Simon Ohm was born into a poor family and had trouble making ends meet for most of his life. However, the German physicist is known today for coming up with Ohm’s law, which describes the mathematical relationship between electrical current, resistance, and voltage.

Ohm’s law says that a steady current (I) flowing through a material with a given resistance is directly proportional to the applied voltage (V) and inversely proportional to the resistance (R). I=V/R is a common way to say that the law is true. Most things, but not all, follow Ohm’s law. People usually call things that don’t do these “nonohmic conductors.” Ohm’s law can be used to explain both magnetic and alternating current circuits with a small change.

Derivation of Ohm’s Law

Ohm’s law says that if the conductivity and other physical conditions (length, cross-section, material, etc.) stay the same, the current flow through a conductor is proportional to the potential difference across the conductor.

Let AB be the leader. At the A end of the conductor, the potential is VA, and at the B end, it is VB. Assume, Va > VB

So, in the conductor, the current will flow from A to B at constant physical conditions. Ohm’s law says that if the current is I, then

(VA – VB ) ∝ I

or it can be written as

VA-VB = RI [where R is a constant named as resistance]

V = RI [If VA – VB = V is supposed]

So, the Final expression will be;

I =V/R 

This constant R is what is meant by “resistance of the conductor.” It is represented by the symbol Ω. If the difference in potential between the conductor’s ends stays the same, the conductor’s resistance goes down as the current goes up, and the current goes up as the resistance goes down.

The formula for ohm’s law

In mathematical terms, Ohm’s Law can be expressed as:

R = V / I

Where:

• R is Resistance in an electrical circuit
• V is the potential difference or applied Voltage across the circuit
• I is the electrical current of the circuit

what do I stand for in ohm’s law?

V = IR, where V is the voltage, I is current, and R is the resistance. If you know the voltage of the battery in the circuit and how much resistance is in the circuit, you can use Ohm’s Law to figure out things about the circuit, like how much current is flowing through it.

what are the 3 Formulas in ohm’s law?

Ohm’s Law gives us the measurement formula of Current (I), Voltage (V), and Resistance (R).

Resistance (R)

A specific property that opposes the flow of current through a conductor is called Resistance. It is a Scalar quantity. Resistance is measured in Ohm so its SI unit is Ohm.

The mathematical Formula of Resistance is:

R = V / I

Definition of SI unit of Resistance

Resistance in an electrical circuit will be 1 Ohm when 1 Ampere current is applied to the circuit whose potential difference is 1 Volt.

Electrical Current (I)

Electric current is the flow of electricity in an electronic circuit and the amount of electricity moving through a circuit. It is a Scalar quantity. Amperes (A) are used to measure it. The more amperes a circuit has, the more electricity is moving through it. SI unit of Current is Ampere.

The mathematical Formula of Current is:

I = V / R

Definition of SI unit of Current

The current of an electrical circuit will be 1 Ampere when the potential difference across the electrical circuit is 1 Volt and Resistance is 1 Ohm.

Voltage (V)

Voltage is the force that comes from the power source of an electrical circuit and pushes charged electrons (current) through a conducting loop, allowing them to do work like turn on a light. Voltage is a scalar value that can be found by multiplying the scalar values of Current and Resistance (scalar).

The mathematical Formula of Voltage is:

V = IR

Definition of SI unit of Voltage

The voltage of the circuit will be 1 Volt when 1 Ampere current will be applied to the circuit whose resistance is 1 Ohm.

Difference b/w Ohmic Conductors & Non-Ohmic Conductors

Ohmic Conductors

The straight line has a slope of 1/R. In an electrical circuit, if the value of the resistance doesn’t change, the slope stays the same. In both the positive and negative quadrants, the slope of the line is always the same. On the Ohmic conductor graph, a part with less resistance has a line with more slope, while a part with more resistance has a line that is much steeper.

Non-Ohmic Conductors

The temperature coefficient for the resistance of the bulb is positive. As the temperature goes up, the resistance of the bulb goes up. When the temperature goes up and the current goes up, the resistance of the filament changes. When the current goes up, the resistance of the filament does not stay the same. So, the incandescent/filament lamp doesn’t follow Ohm’s law, and it’s called a non-ohmic lamp.

Water Pipe Experiment for Ohm’s Law

Ohm’s Law says what happens to the flow of electricity through a resistance when each end of the resistance is given a different voltage. Since we can’t see electrons, comparing electric circuits to water pipes helps us understand them better. A good mechanical system that is similar to an electrical circuit is water flowing through pipes.

In this case, voltage is like water pressure, current is like the amount of water going through the pipe, and resistance is like the size of the pipe. When there is more pressure (voltage), more water will flow through the pipe (current), and the bigger the pipe, the more water will flow through it (lower the resistance).

Experimental Verification of Ohm’s Law

The apparatus required for this experiment is as follows;

Resistor, Ammeter, Voltmeter, Battery, Plug Key, Rheostat.

Experiment Details

• At first, the key K is closed and the rheostat is set so that the ammeter A and voltmeter V show the lowest reading.
• By moving the rheostat’s sliding terminal, the amount of current in the circuit can be slowly increased. During the process, both the amount of current in the circuit and the difference in voltage across the resistance wire R are written down.
• In this way, different sets of voltage and current values can be made.
• The ratio of V/I is worked out for each set of values for V and I.
• When you figure out the ratio V/I for each case, you’ll see that they are almost the same. So, V/I = R, which is the same every time.
• If you plot the current against the difference in potential, you will get a straight line. This shows that the current is equal to the difference in potential.

Applications of Ohm’s Law in everyday life

• Ohm’s law is used a lot in circuit analysis to find things that aren’t known.
• It is used in the process of designing any appliance with electric parts.
• It is used in the fans in our homes that aren’t fancy.
• We can change the speed of the fans in our homes by changing the direction of the regulator. Here, the current going through the fan can be changed by changing how the resistance is set on the regulator. Turn a circular knob on the component to change the resistance at the output terminals. Ohm’s Law lets us figure out the resistance, current, and power flow for any given value of the input.
• It is used in irons and electric kettles.
• The electric kettle and iron both have more than one resistor. So that they can make enough heat, the resistors limit the amount of current that can flow through them. Ohm’s law is used to figure out how big the resistors used in them need to be.
• Ohm’s law is also used to make things like cell phones, laptops, etc. that use electricity.

Limitations of Ohm’s Law

• Ohm’s law doesn’t apply to diodes and transistors, which only let the current flow in one direction, so it can’t be used to describe them.
• Voltage and current won’t stay the same over time for non-linear electrical elements with parameters like capacitance, resistance, etc. This makes it hard to use Ohm’s law. Elements that don’t have a current that is exactly equal to the applied voltage are called non-linear elements. This means that the resistance of these elements changes when the voltage and current are changed. Some non-linear elements are the thyristor, the electric arc, and so on.
• Whether V is positive or negative affects how V relates to I. In other words, if I is current for a certain V, then changing the direction of V while keeping its magnitude the same does not make I-sized currents flow in the opposite direction. A diode is an example of something that does this.
• Ohm’s law only works for conductors made of metal. So it won’t work with things that aren’t made of metal.

FAQ’s

More Articles