What is meant by magnetic flux density?

It is the force acting per unit current per unit length on a straight conductor placed at right angles to the field, B = F/(Il).

What is the unit of magnetic flux density and how does it relate to base units?

The tesla, T, where 1 T = 1 N A⁻¹ m⁻¹, which in base units is 1 kg A⁻¹ s⁻².

What is meant by magnetic flux?

It is the product of the magnetic flux density and the area at right angles to the field, φ = BA cos θ.

What is the unit of magnetic flux?

The weber, Wb, where 1 Wb = 1 T m².

What is meant by flux linkage?

It is the product of the flux through a coil and the number of turns on the coil, Nφ, measured in weber-turns.

How is the flux through a coil affected as the coil is rotated in a fixed magnetic field?

The flux is BA cos θ, where θ is the angle between the field and the normal to the coil, so it is a maximum when the field is along the normal and zero when the field lies in the plane of the coil.

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Electric and Magnetic Fields

Magnetic flux density, flux and flux linkage

1 thing to know
Papers 1 and 3

Overview

Recall questions on flux density and its unit, magnetic flux and flux linkage, and how field strength is shown on a field-line diagram.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Numbers

What are the units of magnetic flux density and magnetic flux, and how is field strength shown on a field-line diagram?

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by magnetic flux density?
Model answer
It is the force acting per unit current per unit length on a straight conductor placed at right angles to the field, B = F/(Il).
2
What is the unit of magnetic flux density and how does it relate to base units?
Model answer
The tesla, T, where 1 T = 1 N A⁻¹ m⁻¹, which in base units is 1 kg A⁻¹ s⁻².
3
What is meant by magnetic flux?
Model answer
It is the product of the magnetic flux density and the area at right angles to the field, φ = BA cos θ.
4
What is the unit of magnetic flux?
Model answer
The weber, Wb, where 1 Wb = 1 T m².
5
What is meant by flux linkage?
Model answer
It is the product of the flux through a coil and the number of turns on the coil, Nφ, measured in weber-turns.
6
How is the flux through a coil affected as the coil is rotated in a fixed magnetic field?
Model answer
The flux is BA cos θ, where θ is the angle between the field and the normal to the coil, so it is a maximum when the field is along the normal and zero when the field lies in the plane of the coil.

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