Magnetic Field due to Current

Electromagnetism

The word electromagnetism is actually combining the words electric current , I (electro) and magnetic field, B (magnetism). Electromagnetism means magnetic field can be produced by the current.

In matriculation syllabus, there are 3 cases of wire that carries current producing magnetic field. These wires are having different forms that are :

1) straight

2) Coil/loop

3) Solenoid.

Equations:

The equations show that they are not the same. For the moment I'm not going to derive the equations of the magnetic field, but I'll just talk a little bit about it in order to give you some useful tips.

I believe many of you might get confused (tertukar) at first with the equations of magnetic field due to the coil and that of straight wire. The important tip here is to look at the form of magnetic field line produced. The current-carrying wire produces circular form of magnetic field, so you need to use your mathematical knowledge here by recalling the formulae for the circumference of a circle that is 2pir. And this is why the equation contains 2pir as the denominator.

Diagram 1

The similarities

(1) From those 3 equations , can you see that the magnetic field, B is directly proportional to the current , I. It means that, the magnetic field around the wire is stronger as we use bigger magnitude of current.

(2) The magnetic field has direction. Its direction is depending on the direction of the current flowing in the wire. Note that we have one well-known method to determine the direction of magnetic field that is by using right hand grip rule, and it always valid for all the three cases. the thumb represents the direction of current, I and the four fingers curl represents that of magnetic field, B and vice versa. You might get a better visualization by referring to Diagram 2 below.

Diagram 2

Thank you,

Mdm Ummi Atiah,

KMPk

~ May it Benefits You➸❤

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