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Physics Lesson 16.2.2 - The Definition of Magnetic Induction

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Welcome to our Physics lesson on The Definition of Magnetic Induction, this is the second lesson of our suite of physics lessons covering the topic of Magnetic Field Produced by Electric Currents, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.

The Definition of Magnetic Induction

From the two experiments above (especially the second one), it is obvious that magnetic field is produced by moving electric charges. Since the current produced in this case is an induced current, we use a quantity called magnetic induction to represent quantitatively the magnetic field. Magnetic induction is a vector quantity and is denoted by B in formulae. It depends on three factors:

  • The amount of current I flowing through the conducting wire when magnetic field is generated,
  • The force F by which we move the magnet towards or away from the coil (greater the force, stronger the magnetic field produced), and
  • The length L of the conducting wire (magnetic induction is inversely proportional to the length of conductor for a constant force and current)

Mathematically, we have:

B = F/I ∙ L

From the above formula, we can determine the unit of magnetic induction B known as Tesla, T. Thus,

1[T] = 1[N/A ∙ m]

In SI units, it becomes

1[T] = 1[kg ∙ m/s2/A ∙ m] = 1[kg/A ∙ s2]

Magnetic induction B is the quantity that represents the magnetic field. It is analogue to the electric field E or gravitational field g discussed in the previous chapters.

Example 1

What is the value of magnetic induction produced by a 3A current flowing through a conducting wire which is 20 cm long? The magnetic force produced in the given point is equal to 30 N.

Solution 1

Clues:

F = 30 N
L = 20 cm = 0.20 m
I = 3 A
B = ?

From the definition of magnetic induction, we have

B = F/I ∙ L
= 30 N/(3 A) ∙ (0.20 m)
= 50 N/A ∙ m
= 50 T

You have reached the end of Physics lesson 16.2.2 The Definition of Magnetic Induction. There are 4 lessons in this physics tutorial covering Magnetic Field Produced by Electric Currents, you can access all the lessons from this tutorial below.

More Magnetic Field Produced by Electric Currents Lessons and Learning Resources

Magnetism Learning Material
Tutorial IDPhysics Tutorial TitleTutorialVideo
Tutorial
Revision
Notes
Revision
Questions
16.2Magnetic Field Produced by Electric Currents
Lesson IDPhysics Lesson TitleLessonVideo
Lesson
16.2.1Two Experiments to Prove the Interaction between Electricity and Magnetism
16.2.2The Definition of Magnetic Induction
16.2.3Magnetic Field Produced by Electric Currents. Right Hand Rule
16.2.4Magnetic Permeability. Relative Permeability. Diamagnetic, Paramagnetic and Ferromagnetic Materials

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