The Conventional Current (Electricity, Physics)
Physics Made Easy
In an electrical circuit, the current is always represented flowing from the positive terminal of a battery to the negative terminal. At the same time, you have learned that electricity in a circuit consists in the motion of negative charge carriers, electrons, flowing from the negative pole to the positive pole. This can be quite confusing for students!
Fundamentally the correct model is that of the electron flow, however, practically, it is consensual to say that a current is a flow of positive charges: this current is called the conventional current. Why do we do that? and why it is OK to do so? This video will answer these two questions.
First, we’ll look at the why. The reasons are historical. So, for the first time, I invite you for a time travel, through some of the history of discovery of electricity. This will make you understand why we use the conventional current model instead of the more accurate electron flow model.
Then, we’ll check that considering a conventional current when studying an electric circuit produces an equivalent impact on the relative charge displacement in the circuit. And we'll also see that does not impact calculation related to the energy conversion that the circuit provides.
I hope these 12 minutes will lift any confusion and allow you to enjoy more your study of electrical sciences!
Structure of the video: 00:00 Electron flow vs. conventional current (Introduction) 00:54 Content of the video « The Conventional Current » 01:08 Benjamin Franklin – The birth of the electrical current 03:10 Joseph John Thomson – The discovery of the electron 05:01 The birth of the conventional current 06:15 Conventional current model – why it is OK to use it (context: motion of charges) 07:39 Conventional current model – why it is OK to use it (context: transfer of energy) 10:06 The arbitrary choice of the sign of the charge of the electron (alt-history) 10:51 Electron flow model vs. conventional current model – which to choose (Conclusion)
Link to Benjamin Franklin’s book : Experiments and Observations on Electricity (Published in 1751) (public domain = it’s free)
Prior knowledge required In order to fully grasp the content of this video, the viewer needs to be familiar with the following concepts already presented in a PME video. _ What is a charge : https://youtu.be/8VN8MDn4CFA _ What is an electric potential: https://www.youtube.com/watch?v=j3GrOKre__0
It would also be useful to know: _ What is a magnetic field: https://youtu.be/NOQK57fgu80?si=VkhRu3i5lXYPrCSu
Credits : The script, the illustrations, the music and the video were produced and presented by Edouard Reny, Ph.D. in solid state chemistry and private tutor in Physical Sciences.
Need help with your high school physics ?: Edouard provides one-on-one private tuition in Physics (face to face or by Skype). If you wish to know more about this, or contact Edouard, visit his website: https://www.physics-tutor.nl/ or this one (for French speakers : https://profdephysique.fr ... https://www.youtube.com/watch?v=XzPOGFgsJfE
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