Ohm’s Law and its Verification

Any movement of electric charge carriers, such as subatomic charged particles like electrons with a negative charge, protons with a positive charge, ions, or holes, is referred to as electric current, electron deficiencies that may be thought of as positive particles.

The quantity of charge passing any point of the wire per unit of time is measured by electric current in a wire with electrons as charge carriers.

The current is in the direction of motion if the moving charges are positive. If they’re negative, the current is moving in the other direction.

Let’s say a charge Q passes an area in time t then we define average current as

i=ΔQ/Δt

We define instantaneous current as,

i=lim Δt→0 ΔQ/Δt

=dQ/dt

Unit of electric current: The SI unit of current is Ampere

Ohm’s Law

G.S. Ohm discovered a basic law governing current flow in 1828, long before the physical mechanism responsible for current flow was found. Consider a conductor with a current I running through it, and V is the potential difference between the conductor’s ends. Then there’s Ohm’s law, which stipulates that

V∝I

Or, it can be written as,

V=RI

R: resistance of the conductor

V: potential difference

I: Current flowing

The SI unit of resistance is ohm, and it is represented by the sign Ω.

The resistance R is determined not only by the conductor’s substance but also by its size.

Alternatively, the current I in a conductor equals the potential difference V across the conductor divided by the resistance of the conductor, or simply I = V/R, and the potential difference across a conductor equals the product of the current in the conductor and its resistance, V = IR. The current can be decreased by adding more resistance or increased by eliminating some resistance in a circuit where the potential difference, or voltage, is constant. The electromotive force, or voltage, E, of a source of electric energy, such as a battery, can also be used to express Ohm’s law

Ohm’s law, with certain adjustments, also applies to alternating-current circuits, where the voltage-current relationship is more intricate than for direct currents. Because the current varies, different forms of resistance to the current, known as reactance, emerge in addition to resistance. Impedance, or Z, is the result of combining resistance and reactance. Ohm’s law applies in an alternating current circuit when the impedance, which is equivalent to the voltage to current ratio, is constant, which is a common occurrence.

Ohm’s Law Magic Triangle

The magic triangle of Ohm’s law depicts the mathematical relationship between voltage (V, also written as U or E), resistance (R), and current (I) in a circuit.

The triangle of Ohm’s law is divided into three sections: Voltage must always be on the top half. The bottom half is then divided into two smaller portions for current and resistance — current is normally on the left, while resistance is on the right, but the order isn’t important. Because most people remember the formula as V = IR, it appears that this is the case.

Verification of Ohm’s Law

In the lab or at home, Ohm’s law can be simply confirmed. A voltmeter, an ammeter, a power supply (dry batteries), resistors, and connecting wires are all required. The following is a basic approach for verifying Ohm’s law:

Four or five dry cells, a thin wire (AB), a voltmeter, an ammeter, a plug key, and thick connecting wires are required. Using one cell, connect the circuit. When not in use, the plug key allows you to turn off the current. When current is passed over a wire for an extended period of time, it becomes fairly hot. This also empties the cell. As a result, only turn on the current when taking measurements by inserting the key into the plug.

The ammeter measures the current I flowing through the circuit, while the voltmeter measures the voltage differential V between the wire’s ends A and B. Take note of these figures. Now, in the circuit, connect two cells in series.

You’ll notice that the voltmeter’s value rises, indicating that a greater potential difference has been applied across wire AB. You’ll see that the ammeter’s reading increases as well. Make a note of the new V and I values. Rep the experiment by connecting three cells in a row, four cells in a row, and so on. Measure the potential difference and current in each scenario. When you compute V / I for each scenario, you’ll notice that it’s nearly identical.

V/I = R, which is another way of presenting Ohm’s law, is a constant. The resistance of the wire AB is denoted by R. If you plot the current I versus the potential difference V on a graph, you’ll see that A straight line will be drawn. The current is proportional to the potential difference.

Water Pipe Analogy for Ohm’s Law

When applied to the water and pipe analogy, Ohm’s Law makes natural sense. We can describe how the three variables interact if we have a water pump that exerts pressure (voltage) to push water across a circuit (current) via a restriction (resistance).

If the resistance to water flow remains constant as the pump pressure rises, the flow rate must increase as well.

Hence we can deduce that

Increase in pressure is equal to Voltage increase
Increase in flow rate is equal to Current increase
Restriction same equals to same resistance

V=IR

Also read: Important Topic of Physics: Specific Heat Capacity

Frequently Asked Questions on Ohm’s Law and Its Verification

What is Ohm's law explain?

Ohm's law states that the current flowing through a conductor is directly proportional to the voltage across it, provided the temperature remains constant.

How do you verify Ohm's law results?

To verify Ohm's law, set up a simple circuit with a battery, resistor, ammeter, and voltmeter. Measure the current and voltage at different points, and check if the V/I ratio remains constant.

What are the 3 formulas in Ohm's law?

The three formulas are V = I*R, I = V/R, and R = V/I, where V is voltage, I is current, and R is resistance.

What is the conclusion of Ohm's law verification?

The conclusion is that if the V/I ratio remains constant at different points in the circuit, Ohm's law is verified.

What is the objective of verification of Ohm's law?

The objective is to confirm the relationship between voltage, current, and resistance as stated by Ohm's law in a real-world scenario.

What happens when current flows through a conductor?

When current flows through a conductor, electrons move through the material, which may generate heat.

Why is it called Ohm's law?

It's called Ohm's law after the German scientist Georg Simon Ohm who first formulated it in 1827.

What is the symbol for ohms?

The symbol for ohms is the Greek letter omega (Ω).