$i$

Definition

$i$ is a symbol commonly used in physics to represent the magnetic flux, which is a measure of the total magnetic field passing through a given surface. It is a fundamental concept in electromagnetism and is closely related to the phenomenon of electromagnetic induction.

5 Must Know Facts For Your Next Test

1. Magnetic flux, $i$, is defined as the product of the magnetic field strength, $B$, and the area, $A$, over which the field is measured: $i = BA$.
2. The unit of magnetic flux is the weber (Wb), which is equivalent to tesla-square meter (T·m^2).
3. Magnetic flux is a vector quantity, meaning it has both magnitude and direction, and is typically represented using the right-hand rule.
4. Changes in magnetic flux over time are the basis for the phenomenon of electromagnetic induction, as described by Faraday's law.
5. In the context of back EMF, $i$ represents the magnetic flux linking the windings of an electric motor or generator, and its rate of change determines the magnitude of the back EMF.

Review Questions

• Explain the relationship between magnetic flux, $i$, and the magnetic field strength, $B$.
  • The magnetic flux, $i$, is directly proportional to the magnetic field strength, $B$, and the area, $A$, over which the field is measured. Mathematically, this relationship is expressed as $i = BA$. The magnetic flux represents the total number of magnetic field lines passing through a given surface, and it is a vector quantity, meaning it has both magnitude and direction.
• Describe how changes in magnetic flux, $i$, are related to the phenomenon of electromagnetic induction, as described by Faraday's law.
  • According to Faraday's law of electromagnetic induction, the electromotive force (EMF) induced in a closed circuit is proportional to the rate of change of the magnetic flux, $i$, through the circuit. Specifically, the induced EMF is equal to the negative of the time rate of change of the magnetic flux: $ extbackslashvarepsilon = -N extbackslashfrac{di}{dt}$, where $N$ is the number of turns in the circuit. This relationship is the foundation for the operation of electric motors, generators, and various other electromagnetic devices.
• Explain the role of magnetic flux, $i$, in the context of back EMF in electric motors and generators.
  • In electric motors and generators, the magnetic flux, $i$, linking the windings of the device plays a crucial role in the generation of back EMF. Back EMF is the voltage that is induced in the device due to the changing magnetic flux, and it opposes the applied voltage, reducing the current flow and the motor's or generator's output power. The magnitude of the back EMF is directly proportional to the rate of change of the magnetic flux, $ extbackslashfrac{di}{dt}$, as well as the number of turns in the windings. Understanding the relationship between $i$ and back EMF is essential for the proper design and operation of these electromagnetic devices.

Related terms

Magnetic Flux Density:

The magnetic flux density, also known as the magnetic field strength, is a vector field that describes the magnitude and direction of the magnetic field at a given point in space.

Faraday's Law of Electromagnetic Induction: Faraday's law states that the electromotive force (EMF) induced in a closed circuit is proportional to the rate of change of the magnetic flux through the circuit.

Back Electromotive Force (Back EMF): Back EMF is the voltage that is induced in an electric motor or generator that opposes the applied voltage, reducing the current flow and the motor's or generator's output power.