SI Unit of Magnetic Field Overview
The term "magnetic field" describes the region surrounding a magnet that produces magnetic energy as a result of the motion of electric charges. The letters "B" or "H" stand for the magnetic field.
- The magnetic field known as the B-field is created when a magnet pulls on a charged particle in motion.
- In contrast to a B-field, an H-field occurs when an item is enclosed in a material.
Tesla is the SI unit for Magnetic Field. (T). The International System of Units' derived measure for magnetic field strength (also known as magnetic flux density) is the tesla (symbol - T). One Weber per square meter is equivalent to one tesla. The magnetic field unit is useful for measuring the magnetic force that surrounds any magnetically-active item.
SI Unit of Magnetic Field Strength
Magnetic field strength is a measure of the force exerted by a magnetic field on a moving charge or another magnetic field. It is measured in units of tesla (T), named after the famous physicist Nikola Tesla.
One tesla is defined as the magnetic field strength generated by a current of one ampere flowing through a wire of one meter in length, placed perpendicular to the wire, at a distance of one meter from the wire. However, in practice, magnetic fields are often measured in smaller units such as millitesla (mT) or microtesla (µT).
SI Unit of Magnetic Field
B and H stand for the magnetic field, respectively.
- Amperes per meter is the SI unit for the magnetic field of H.
- Teslas or Newtons per meter per ampere are the SI units for magnetic fields in the B axis.
The magnetic field is measured using the tesla SI measurement. (T). A magnetic field is defined as one tesla when a charge of one coulomb encounters a force of one newton while traveling at a speed of one m/s perpendicular to the magnetic field.
In terms of how it affects the environment, a magnetic field can be described in a number of different ways. There are B-fields and H-fields as a result.
Other Unit of Magnetic Field
The following table provides a list of common units used to measure magnetic field strength:
Unit | Abbreviation | Equivalent |
| Tesla | T | 1 T = 10,000 G |
| Gauss | G | 1 G = 0.0001 T |
| Millitesla | mT | 1 mT = 0.001 T |
| Microtesla | µT | 1 µT = 0.000001 T |
The conversion between these units is important, as some devices, such as MRI machines, use different units of measurement.
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SI Unit of Magnetic Field Applications
Magnetic field strength has many practical applications in our daily lives. For example, magnetic fields are used in MRI machines to produce detailed images of the body's internal organs and tissues. Magnetic field strength is also used in the design and manufacturing of electric motors and generators.
In addition, magnetic field strength is used in the design of safety standards for electronic devices. For example, the safe levels of magnetic field exposure for workers in various industries are regulated by government agencies, such as the Occupational Safety and Health Administration (OSHA).
SI Unit of Magnetic Field: Examples
- The magnetic field of a bar magnet, which creates a field that flows from the north pole to the south pole of the magnet.
- The magnetic field of the Earth, which creates a field that flows from the geographic north pole to the geographic south pole.
- The magnetic field of a current-carrying wire, which creates a field that flows in concentric circles around the wire.
- The magnetic field of a solenoid, which creates a field that flows through the center of the solenoid and is uniform in strength.
- The magnetic field of an MRI machine, which creates a strong, uniform field that is used to produce detailed images of the body's internal organs and tissues.
- The magnetic field of a speaker, which creates a field that interacts with a magnet to produce sound waves.
Representation of Magnetic Field
- Magnetic field lines are used to represent the direction and strength of a magnetic field in a given space.
- Magnetic field lines are imaginary lines that indicate the direction of the magnetic field at different points in space.
- Magnetic field lines are drawn in such a way that they form closed loops around a magnet or a current-carrying conductor.
- The direction of the magnetic field is indicated by the orientation of the magnetic field lines.
- The lines always flow from the north pole to the south pole of a magnet or from the positive end to the negative end of a current-carrying conductor.
- The density of magnetic field lines indicates the strength of the magnetic field, with denser lines indicating a stronger magnetic field.
- Magnetic field lines never intersect because the direction of the magnetic field cannot change instantaneously.
- Magnetic field lines can be used to predict the behavior of magnets and current-carrying conductors in a given space.
- The representation of magnetic field lines is an essential tool in the study of electromagnetism and is used in various applications, including the design of electrical motors, MRI machines, and compasses.
SI Unit of Magnetic Field: Magnetic Force
- The interaction of magnetic fields produces a force that can either be attractive or repulsive. This force is known as the magnetic force.
- If an electric charge (q) with velocity (v) is present at a particular location (r) and time (t) in the presence of an electric field (E(r)) and a magnetic field (B(r)), the resulting force on the charge can be expressed as F = q[E(r) + B(r)], which comprises both the electric force (Felectric) and the magnetic force (Fmagnetic).
- The Lorentz Force, also known as the magnetic force on a charged particle, was derived by H.A Lorentz based on the experiments conducted by Ampere and other researchers.
Magnetic Field in a Straight Wire due to Current
According to Ampere's Law, a straight wire carrying a current produces a magnetic field that is directly proportional to the current and inversely proportional to the distance from the wire. The magnetic field lines form concentric circles around the wire, with the wire lying at the center of the circles.
The magnitude of the magnetic field (B) at a distance (r) from the wire is given by the equation:
B = (μ₀* I) / (2π * r)
where μ₀is the permeability of free space, I is the current flowing through the wire, and π is the mathematical constant pi (approximately equal to 3.14159).
The direction of the magnetic field can be determined using the right-hand rule. If the thumb of your right-hand points in the direction of the current flow, then the curled fingers of your hand will indicate the direction of the magnetic field lines around the wire.
Magnetic Field on a Current-Carrying Circular Loop
When an electric current flows through a circular loop, a magnetic field is produced in the space surrounding the loop. The magnetic field is directly proportional to the current flowing through the loop and is strongest at the center of the loop.
The magnitude of the magnetic field (B) at the center of the loop is given by the equation:
B = (μ₀* I) / (2 * r)
where μ₀is the permeability of free space, I is the current flowing through the loop, and r is the radius of the loop.
The direction of the magnetic field can be determined using the right-hand rule. If you wrap your right hand around the loop so that your fingers curl in the direction of the current, then your thumb will point in the direction of the magnetic field lines.
The magnetic field produced by a circular loop has several practical applications. For example, it is used in the construction of electromagnets, which are used in a wide range of devices, including electric motors, generators, and MRI machines. The magnetic field produced by a circular loop can also induce an electric current in a nearby conductor, which is the basis of many electrical transformers.
Magnetic Field in a Solenoid
A solenoid is a long, cylindrical coil of wire that is tightly wound to produce a magnetic field when an electric current flows through it. The magnetic field produced by a solenoid is like that produced by a bar magnet, with the field lines running from one end of the solenoid to the other.
The magnitude of the magnetic field (B) inside a solenoid is directly proportional to the current (I) flowing through the solenoid and the number of turns per unit length (N/L) of the wire making up the solenoid. The magnetic field is given by the equation:
B = μ°I N/L
where μ₀is the permeability of free space, N is the number of turns in the solenoid, L is the length of the solenoid, and I is the current flowing through the solenoid.
SI Unit of Magnetic Field: Things to Remember
- H and B, which stand for magnetic flux and field strength respectively, are used to depict magnetic fields.
- The SI measure of B is Teslas or Newtons per meter per ampere, whereas the SI unit of magnetic field, H, is amperes per meter.
- Lines of magnetic fields cannot intersect one another. They are perpetual loops that never stop.
- Gauss is the smallest magnetic field measure in the CGS system.
- 1T equals 10,000G is the relationship between Gauss and Tesla.
- The Lorentz Force rule states that the vector product of magnetic field and velocity is known as q [v X B].
- The vector sum of forces is zero if v and B are parallel or antiparallel. The magnetic pull can only be felt by a moving charge.
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SI Unit of Magnetic Field: Previous Year Questions
What is the SI unit of magnetic field?
Answer:Tesla
A wire carrying a current of 2 A produces a magnetic field of 10^-5 T at 5 cm. What is the magnetic field strength at 10 cm from the wire?
Answer:2 × 10^-6 T
A solenoid has a length of 20 cm and a radius of 2 cm. It has 500 turns and carries a current of 5 A. What is the magnetic field strength at the centre of the solenoid?
Answer: 4π × 10^-4 T
A bar magnet has a magnetic moment of 4.0 A-m² and is placed in a magnetic field of 0.5 T. What is the torque experienced by the magnet if it is aligned at an angle of 60 degrees to the field?
Answer: 1.2 N-m
A circular coil of radius 10 cm and 20 turns carries a current of 5 A. What is the magnetic field strength at the centre of the coil?
Answer: 2π × 10^-3 T
The magnetic field strength at a point near a current-carrying wire is 2 × 10^-4 T. If the current in the wire is doubled, what will be the new magnetic field strength at the same point?
Answer: 4 × 10^-4 T
A long straight wire carries a current of 10 A. What is the magnetic field strength at a distance of 5 cm from the wire?
Answer: 2 × 10^-5 T