Ohm’s Law is a fundamental principle in electrical engineering and physics that describes the relationship between voltage, current, and resistance in an electrical circuit. It was formulated by the German physicist Georg Simon Ohm in 1827.
What is Ohm Law | Define Ohm's Law
Ohm’s law is a simple rule that tells us the relationship between voltage, current, and resistance in electrical devices.
State Ohm's Law
Ohm law states that:
- There is a definite relationship between voltage, current, and resistance.
- Voltage (V) = Current (I) × Resistance (R)
Where:
- V: Voltage, which represents the “pressure” of electricity (measured in volts).
- I: Current, which represents the flow of electricity (measured in amperes).
- R: Resistance, which acts to stop the flow of electricity (measured in ohms).
Ohms Law Formula
The formula representing Ohm’s Law is expressed as V = IR.
Ohm Symbol
Ohm’s Law is represented by the symbol Ω, which stands for ohm. Ohm’s law is pivotal for understanding how electronic devices function and for ensuring their safe operation.
It provides insights into how much power an electrical device consumes or how much heat it generates due to resistance.
By applying this principle effectively, professionals can optimize circuit designs for efficiency and safety in various applications ranging from simple household appliances to complex industrial machinery.
Ohm's Law Example
First, let’s take a bulb:
- If the voltage across the bulb is increased, the current (electric flow) in the bulb will also increase, and the bulb will shine brighter.
- If a resistance is connected in series with the bulb, the current will reduce and the bulb will glow dimly.
Verification of Ohm's Law
A simple experiment is used to verify Ohm law that shows the relationship between voltage, current and resistance in an electric circuit.
In which some materials are taken:
- A DC power supply (battery or voltage source)
- A resistor (fixed or variable)
- An ammeter (to measure current)
- A voltmeter (to measure voltage)
- Connecting wires
- A switch (optional)
Connect all these according to the given diagram. Now, when the terminal is closed, current flows in the circuit. Note the reading of the voltmeter and ammeter located in the circuit. Similarly, note the reading by adjusting the rheostat to different positions. We observe that
Ohm's Law Graph
जब x- अक्ष और y-अक्ष पर एक ग्राफ draw करते है
- y-अक्ष पर वोल्टेज (V) और x-अक्ष पर धारा (I) को लेते है।
- The graph is a straight line passing through the origin, which shows that the voltage is directly proportional to the current.
Voltage Current Resistance Relationship
Ohm’s Law is a fundamental principle in the field of electronics and electrical engineering, providing a clear relationship between voltage, current, and resistance in an electrical circuit.
The law is named after the German physicist Georg Simon Ohm, who first formulated it.
To state Ohm Law succinctly, the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance of the conductor.
Practical Applications of Ohm's Law
Ohm law is not just a theory, but it is also essential and useful in our daily lives. Let us understand how useful resistance law is with some examples:
Home Electrical Wiring Design: When installing any electrical appliance (like a bulb, fan, or heater) in the home, Ohm’s law helps you to determine how much voltage, current, and resistance will be required.
Resistor Selection: When designing electronic devices or circuits, you need various resistors. Ohm’s Law helps determine what resistance is required to allow the correct current to flow.
Smartphones and electronic devices: In smartphones, laptops, and other small electronic devices, Ohm’s law is used to design the various components of the device (e.g., battery, processor, screen) to provide the correct voltage and current.
Electric motors and generators: Ohm’s law helps balance voltage, current, and resistance in motors and generators to ensure that the motor operates properly and energy is used efficiently.
Solar Panel System: Ohm’s law is very important for the proper operation of a solar panel. The correct balance of voltage and current from the solar panel has to be maintained so that the battery can charge appropriately.
Signal transmission and telecommunication: Ohm’s law is used in wireless power transmission project or wired communication to determine how to send a signal without loss. It controls current and resistance.
Parking sensors and other sensor devices: Ohm’s law is also used in parking sensors and other electronic sensor devices. When data is taken from the sensors, Ohm’s law is used to ensure that the data is correct.
Fuses and Circuit Breakers: Ohm’s law is also used in the design of electric fuses and circuit breakers. These devices prevent overload current in electric circuits.
Limitations of Ohm's Law
Ω(ohm symbol) law is a fundamental and widely applied principle in electrical engineering, but it has certain limitations and does not apply universally to all materials and conditions. Below are some significant limitations:
Non-Linear Behavior of Certain Materials
Ohm’s law states that the relationship between voltage and current is linear, i.e., current increases proportionally with the applied voltage. However, some substances and devices do not follow this linear relationship. These are known as non-ohmic substances.
Diodes and transistors are non-ohmic, as they allow current to flow in only one direction (for diodes) or behave in a nonlinear way under varying voltage conditions (like in transistors). The current-voltage relationship in these devices is not linear and cannot be described by Ω(ohm symbol) Law.
Temperature Dependence
Ohm’s law requires that resistance be constant, but in real-world situations, especially at high currents, temperature rise significantly affects resistance, making the direct application of Ω(ohm symbol) law more complicated.
Because when current flows through a resistor, it heats up. This heating can increase the resistance of the resistor, which changes the flow of current and violates the assumptions made by Ohm’s Law.
High-Voltage or High-Current Effects
At very high voltages or currents, the behaviour of materials changes dramatically. Resistance is no longer constant, and breakdown of the material occurs, such as an electric arc or dielectric breakdown, making Ohm’s law inapplicable.
Superconductors
Superconductors are materials that, at very low temperatures, exhibit zero electrical resistance.
Law of resistance does not apply to superconductors, as their resistance is effectively zero, and current can flow indefinitely without any voltage drop.
Capacitors and Inductors
Ohm’s law applies only to direct current (DC) circuits and purely resistive materials. In alternating current (AC) circuits that use capacitors and inductors, the behaviour is more complex because the impedance (opposition to AC) depends on frequency and phase angle.
Capacitors and inductors cause a phase shift between voltage and current, making the simple application of law of resistance inadequate for such components.
High-Frequency Signals
At high frequencies, the current becomes concentrated at the surface of the conductor rather than flowing through the entire cross-section of the material.
This phenomenon is called the skin effect, which causes the effective resistance to increase with frequency.
The skin effect causes the current to be restricted to a thinner layer of the conductor. Therefore, Ohm’s Law may not accurately reflect the actual current flow.
Do not apply insulating materials
Ω(ohm law) law doesn’t apply to insulating materials or materials that do not exhibit linear resistance.
Insulators like rubber or plastic have very high resistance and do not allow significant current to flow, so Ohm’s Law is not applicable in analyzing such materials.
Complex Materials and Mixed States
Heterogeneous Materials like carbon nanotubes or graphene with complex structures. Ohm’s law may not apply in the traditional sense because the material properties are not uniform across the material.
What is the Condition of Ohm's Law
To use Ohm’s law accurately and effectively, certain conditions must be followed. Here are some key conditions to know:
The Material Must Be Ohmic (Linear)
Law of resistance applies only to ohmic materials, meaning materials that have a linear relationship between voltage and current.
Constant Temperature
For Ohm’s law to apply accurately, the temperature of the material must remain constant, or at least the resistance of the material must not vary significantly with temperature.
DC (Direct Current) Circuits
Ω(ohm symbol) law is most accurate for direct current (DC) circuits where current flows in only one direction. In DC circuits, the relationship between voltage and current is linear and straightforward.
No Excessive Voltage or Current
The high voltage may cause the air to ionize and conduct electricity, or the high current may cause the resistance of the material to change dramatically due to excessive heating. In these extreme situations, Ohm’s law does not hold.
Steady-State Conditions
For Ohm’s Law to be accurate, the system should be in a steady-state condition, meaning the current and voltage must be constant over time.
Uniform Material Composition
Homogeneous Materials: The material through which the current is flowing must be homogeneous and uniform.
Ideal Conditions
For Ohm’s Law to be followed perfectly, the components must behave ideally, meaning there should be no parasitic elements such as stray capacitance or inductance.
Modern Applications of Ohm's Law
Despite Ohm’s law being one of the oldest principles in electrical engineering and physics, it is widely used in modern technology and applications.
In the context of today’s advanced technologies, Ω(ohm symbol) law is still essential for understanding and designing electrical and electronic systems. Some of the modern applications of Ohm’s law are as follows:
Smartphones and Consumer Electronics
In modern smartphones, tablets, and laptops, Ohm’s Law is used to design efficient battery charging circuits. By applying Ω(ohm symbol) Law, engineers calculate the proper current that should flow into the battery from the charger to avoid overcharging or overheating.
In electronic devices such as smartwatches, fitness trackers and gaming consoles, Ohm’s Law is used in processors, memory and display systems to ensure proper voltage levels are delivered to internal components.
This ensures that the devices receive the correct amount of power without damaging them.
LED Lighting Systems
In LED circuits, Ohm’s Law is used to limit the current flowing through the LED to prevent it from burning out.
Since LEDs are current-sensitive, a resistor is used to limit the current, and law of resistance helps determine the right resistance needed based on the supply voltage and the LED’s voltage requirements.
Ohm’s law helps engineers design LED lighting strips for commercial and residential use. Using Ohm’s law, they calculate the exact current needed to ensure proper brightness.
Power Electronics and Renewable Energy Systems
Engineers use Ohm’s law to calculate the voltage and current supplied by solar panels to charge batteries efficiently.
Inverters convert direct current to alternating current. Ω(ohm symbol) law plays an important role in determining the size of their components and controlling power transfer in systems.
Ohm’s law helps design inverters that ensure the electrical grid receives the correct voltage and current.
In electric vehicles, battery management systems use Ohm’s law to regulate the charging and discharging of the battery, thereby optimizing the range and longevity of the car.
Integrated Circuits (ICs) and Microelectronics
Engineers use in the design of microchips, such as those found in processors, memory, and sensors, with the help of law of resistance.
In modern transistors such as amplifiers and oscillators, Ohm’s Law is used to bias transistors correctly, controlling the current and voltage to optimize performance.
Internet of Things (IoT)
In IoT devices, which are often battery-powered and need to be energy-efficient, Ohm’s Law helps engineers design low-power circuits.
Using law of resistance, they select resistors and other components to ensure that devices consume minimal energy while still functioning efficiently.
Electric Power Distribution and Grid Systems
Ohm’s law is used in innovative grid systems. By calculating voltage drops and current flow across various parts of the grid, engineers ensure that the right amount of power reaches consumers with minimal loss.
In the design of power transformers, law of resistance helps determine the correct voltage and current parameters to step up or down the voltage as per the utility requirement for efficient power distribution.
3D Printing and Robotics
In 3D printing, Ohm’s Law is used to control the power supply to the motors and heating elements.
For accuracy and quality of the printed objects, ensure the printer operates at precise temperatures and movement speeds.
Medical Devices
In medical devices like ECG machines or pacemakers, Ω(ohm symbol) Law helps in designing circuits.
This ensures correct voltage and current are supplied to sensors, amplifiers, and other components, providing accurate readings and safe operation.
Electric Aircraft and Drones
Ohm’s law helps the batteries used in electric aeroplanes and drones charge properly, deliver power to the motors efficiently, and keep the system balanced.
Conclusion
George Simon Ohm state and explain Ohm’s law. Currently, it guides engineers and scientists in designing efficient electrical systems, from household appliances to complex electronics. In the past, it paved the way for innovations in electrical technology. In the future, Ohm’s Law will play a vital role in the development of energy-efficient devices, renewable energy systems, and new technology. Its simplicity and applicability will benefit generations to come.
FAQ
1. Ohm Law Derivation
Law of resistance gives the relationship between voltage (V), current (I), and resistance (R) in an electric circuit. This law states that the current passing through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conductor.
V=IR
2. Vector Form of Ohm's Law
The vector form of Ohm’s Law is used when considering the direction and magnitude of electric fields, current, and resistance in a three-dimensional space. It is especially useful in the context of more complex circuits or materials.
vector form of Ohm’s Law is
J=σE
3. What is the microscopic form of Ohm's law?
microscopic form, Ohm’s Law is expressed as:
J=σE
Where:
- J is the current density vector (A/m²), which shows the amount of electric current flowing per unit area per unit of time at a point in the material.
- σ is the electrical conductivity (S/m), which shows material property that quantifies how easily the material allows current to flow.
- E is the electric field vector (V/m), which shows the force driving the movement of charge carriers within the material.
4. What is an Ohmic Conduction
Ohmic conduction refers to the type of electrical conduction where the current flowing through a material is directly proportional to the applied voltage, and the relationship between current and voltage follows Ohm’s Law.
I am an engineer in a government department and also a blogger. I write posts on topics related to electrical and electronics engineering.