- What is a Magnetic Field?
- SI Unit of Magnetic Field
- CGS Unit of Magnetic Field
- Tesla vs Gauss
- Magnetic Field Strength Unit
- Units of Magnetic Flux vs Magnetic Field
- Magnetic Field Formula
- Earth's Magnetic Field Unit
- Magnetic Field in Real-Life Applications
- Common Questions
- Magnetic Field Units in NEET and JEE
- Final Summary
- FAQs Unit of Magnetic Field
Unit of Magnetic Field
By Swati Singh
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Updated on 25 Apr 2025, 15:29 IST
Understanding the unit of magnetic field is essential in physics, especially when studying electricity, magnetism, and their applications. This article will explain what magnetic fields are, what units are used to measure them, and how those units are applied in real life.
What is a Magnetic Field?
A magnetic field is the area around a magnet or a moving electric charge where magnetic forces can be felt. It can affect other magnets or moving charges nearby. The strength and direction of this magnetic effect are what we measure.
SI Unit of Magnetic Field
The SI unit of magnetic field is the Tesla (T). It is named after Nikola Tesla, a scientist known for his work in electricity and magnetism.
1 Tesla (T) = 1 Weber per square meter (Wb/m²)
This means that if one weber of magnetic flux passes through an area of one square meter, the magnetic field is one Tesla.
CGS Unit of Magnetic Field
In the CGS (Centimeter-Gram-Second) system, the unit of magnetic field is the Gauss (G).
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1 Tesla = 10,000 Gauss
This unit is smaller than the Tesla and is commonly used in older physics textbooks or specific scientific contexts.
Tesla vs Gauss
| Quantity | Tesla (T) | Gauss (G) |
| System | SI | CGS |
| Larger or Smaller | Larger unit | Smaller unit |
| Conversion | 1 T = 10,000 G | 1 G = 0.0001 T |
So, if a magnetic field is 0.5 T, it is equal to 5,000 Gauss.
Magnetic Field Strength Unit
Magnetic field strength is also called magnetic field intensity, and its unit is Ampere per meter (A/m) in the SI system.
This is different from magnetic flux density, which is measured in Tesla. While magnetic flux density shows the concentration of magnetic field lines, magnetic field strength shows the force that creates the magnetic field.
Units of Magnetic Flux vs Magnetic Field
| Concept | Unit | Symbol |
| Magnetic Field (B) | Tesla (T) | T |
| Magnetic Field (CGS) | Gauss (G) | G |
| Magnetic Field Strength | Ampere per meter | A/m |
| Magnetic Flux | Weber (Wb) | Wb |
Magnetic Field Formula
The basic formula for calculating magnetic field in a wire is:
B = (μ × I) / (2πr)
Where:
- B = magnetic field (in Tesla)
- μ = magnetic permeability
- I = current (in Amperes)
- r = distance from wire (in meters)
Earth's Magnetic Field Unit
The Earth’s magnetic field is around 25 to 65 microteslas (μT), which is 0.25 to 0.65 Gauss. That’s a very weak magnetic field compared to machines like MRI scanners.
Motors and Generators – Depend on magnetic fields for rotation
Measuring Magnetic Fields in Labs – Use devices like gaussmeters to measure in Tesla or Gauss
Common Questions
What is the unit of magnetic field?
The unit of magnetic field is Tesla (T) in the SI system.
Is Gauss an SI unit?
No, Gauss is part of the CGS system. The SI unit is Tesla.
How to convert Gauss to Tesla?
1 Gauss = 0.0001 Tesla
Why is Tesla the unit of magnetic field?
Tesla is the SI unit named to honor Nikola Tesla for his contributions to electromagnetism.
Magnetic Field Units in NEET and JEE
Students preparing for NEET, JEE, or board exams in Class 12 should remember:
- SI Unit: Tesla (T)
- CGS Unit: Gauss (G)
- Field Strength: Ampere/meter (A/m)
- Flux: Weber (Wb)
Final Summary
Understanding the unit of magnetic field is crucial for solving problems in electromagnetism. The Tesla is the SI unit, while Gauss is used in the CGS system. Knowing how to convert and compare these units helps you answer exam questions easily and apply the concepts in real life.
FAQs Unit of Magnetic Field
What is the unit of magnetic field in the SI system?
The SI unit of magnetic field is Tesla (T). It measures the magnetic flux density, which tells us how strong and concentrated a magnetic field is.
What is the CGS unit of magnetic field?
In the CGS (Centimeter-Gram-Second) system, the unit of magnetic field is Gauss (G). It is a smaller unit than Tesla.
How are Tesla and Gauss related?
1 Tesla = 10,000 Gauss
1 Gauss = 0.0001 Tesla
This means Tesla is a much larger unit compared to Gauss.
Why is Tesla used as the unit of magnetic field?
The unit Tesla is used in the SI system to honor the scientist Nikola Tesla for his major contributions to the field of electromagnetism.
What is the difference between magnetic field and magnetic field strength?
Magnetic field (or magnetic flux density) is measured in Tesla (T).
Magnetic field strength (also called intensity) is measured in Ampere per meter (A/m) and shows the source or cause of the magnetic field.
What is magnetic flux and how is it related to the magnetic field?
Magnetic flux is the total magnetic field passing through an area. Its SI unit is Weber (Wb).
The magnetic field (Tesla) = Magnetic flux (Weber) ÷ Area (m²)
How strong is Earth’s magnetic field?
The Earth’s magnetic field is about 25 to 65 microtesla (μT), which is 0.25 to 0.65 Gauss — very weak compared to artificial magnets used in machines.
Which unit is used in MRI machines?
MRI (Magnetic Resonance Imaging) machines often use very strong magnetic fields, measured in Tesla (T). A typical MRI machine may use 1.5 T or 3 T magnets.
Why should students learn both Tesla and Gauss?
Students should learn both because:
Tesla is used in modern physics and the SI system.
Gauss is still found in older texts and is common in certain scientific applications.
Understanding both helps in converting units and solving questions in exams like NEET and JEE.