Jidhafs Secondary Technical Boys School
Prepared by
SAHAD
INTRODUCTION
The modern world is entirely dominated by electricity and our ability to control
it. How often have you stopped to think about all the things you take for
granted- such as the light in your house, the air conditioner, the water heater,
the toaster, and electronic gadgets?None of this would function without
Ohm’s law! This fundamental principle discovered about two hundred years
ago made it possible to create machines that built the world we know today.
So what does Ohm’s law say? Let’s find out!
CONTENT
Ohm’s Law Explanation
Source
When learning about electrical circuits, there are three important
parameters you need to know:
Voltage (v): Voltage measures the electrical potential difference across
two points. Think of it as a pressure source in an electrical circuit that
pushes electrons (current) through the wires. The flow of electrons gets
work done, such as illuminating a bulb or running a motor.
Current (I): Current measures how many electrons flow across a given
point under unit time. Think of current as the number of electrons flowing in
the wires. The unit of current is ampere (A) or amps. 1 ampere of current
equals 1 coulomb (6.24 x 1018) electrons flowing past a point in 1 second.
It is like measuring how much water flows out of a garden hose in under 1
second.
Resistance (R): Simply put, resistance is how much a wire or conductor
resists the current flow in an electrical circuit. Copper has a low resistance;
hence it is used as a conductor, whereas rubber has such a high resistance
that it completely restricts the flow of current. Different materials have
different levels of resistance to the flow of current.
Define Ohm’s Law: This law states that the current flowing in a conductor is
directly proportional to the voltage across the conductor. Mathematically
the ohm's law equation states that: V ∝ I Or V=RI
R is the constant of proportionality which is resistance. The value of R is
different for different conductors.
Source
Ohm’s law draws a relationship between voltage, current, and resistance.
The ohm's law formulas can be used to deduce the current flowing in a
conductor or the resistance or the voltage if any of the two values is known.
Calculating Electrical Power Using Ohm’s Law
The rate at which energy is converted from the electrical energy of the
moving charges to some other form of energy like mechanical energy, heat
energy, energy stored in magnetic fields or electric fields, is known as
electric power. The unit of power is the watt. The electrical power can be
calculated using Ohm’s law and by substituting the values of voltage,
current and resistance.
Formula to find power
When the values for voltage and current are given,
When the values for voltage and resistance are given,
When the values for current and resistance are given,
Ohm’s Law Pie Chart
To better understand the relationship
between various parameters, we can take
all the equations used to find the voltage,
current, resistance and power, and
condense them into a simple Ohm’s Law
pie chart as shown below.
Ohm’s Law Applications
The main applications of Ohm’s law are:

To determine the voltage, resistance or current of an electric circuit.


Ohm’s law maintains the desired voltage drop across the electronic
components.
Ohm’s law is also used in DC ammeter and other DC shunts to divert
the current.
Limitations of Ohm’s Law
Following are the limitations of Ohm’s law:


Ohm’s law is not applicable for unilateral electrical elements like
diodes and transistors as they allow the current to flow through in one
direction only.
For non-linear electrical elements with parameters like capacitance,
resistance etc. the ratio of voltage and current won’t be constant with
respect to time making it difficult to use Ohm’s law.
SOME PRACTICAL OHM LAW EXAMPLES:

Ohm’s law is the principle behind the working of safety fuses and
circuit breakers. Fuses are rated for a fixed current and melt
when more current flows through.

Electronic device design.

Speed control of fans using a potentiometer.

Functioning of heating elements.
CONCLUSION

Ohm’s law gives a conductor the relationship between voltage,
current, and resistance.

Voltage measures the electrical potential difference across two points
in a conductor.

Current measures how many electrons flow across a given point
under unit time.

Resistance is how much a wire or conductor resists the current flow
in an electrical circuit.
RESOURCES
https://www.inspiritvr.com/general-physics/electric-current/ohms-lawstudy-guide
https://byjus.com/physics/ohms-law/
https://en.wikipedia.org/wiki/Ohm%27s_law