Electricity & Magnetism Hand Rules (part one)

The Tabletop Explainer is an intermittent educational vlog presenting answers to viewer questions, brief science lessons, and ideas for teachers and students. It is a feature of my blog "Tilts at Windmils" which can be found at http://www.davidcolarusso.com/blog/

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• physics
• demos
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• right
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• hand
• rules
• magnetic
• field
• lines
• force

[pithikoulis]

I have a question: As you say the force is applied on the charge. Why does that make the whole foil move upwards or downwars? Is it that the magnetic field pushes the electrons upwards while they pass through the foil or did I grasp it wrong?

[dcolarusso]

@pithikoulis that's the basic idea. The current moving through the wire is made up of electrons (charged particles) and since they are moving through a magnetic field, they feel a force, either up or down, and they carry the foil with them.

[dnmn8r]

Hey great and very helpful video.

Just one question, you said that "DC current is the movement of a negative charge". I'm not sure if this is just an Australian thing, but i thought that in physics we always show current as the movement of a positive charge (and not the electrons).

[dcolarusso]

dnmn8r, When the study of electricity fist began, people were under the impression that it was the flow of positive current, we have since discovered that it is in fact the movement of negatively charged electrons. Because of this historical accident, however, we sometimes still refere to this imaginary positive current. When we do, it usually is called "conventional current." It gives you most of the right answers, but doesn't actually reflect reality. I'd suggest Googling conventional current.

[tulaconalas]

i still dont get the hand stuff he told.. well

[SalviaDivinorumBlog]

electricity flows from positive to negative not from black to red.

[MrJonkelp]

really informative and interesting

[31896eneri]

when he switched the direction of the wires it will make red negative (red -)and black the positve(black +) . So the thumb must now point to the right (red to black).flip the left hand over so palm faces downward to make the thumb point to the right. The direction of the magnetic field didn’t change so the fingers still points out of the screen.that will make your palm face upward.

[MrGrzv]

@dcolarusso Hi, nice presentation. Let me add something to the debate. Yes, electricity is movement of electrons. Yes, they are negatively charged. But! Their charge is also matter of convention. Electrons don't know whether they are positively or negatively charged. If scientists agreed they carry plus on their small shoulders, they would be perfectly happy with it. Science is loaded with such conventions leading to misunderstanding between physicists, chemists and mathematicians...