23 Jul 2011

Current and Voltage


Form 3, this is the video that I used for my explanation on Current and Voltage.
The thing that you need to remember is the concept of what is current and what is voltage. Of course you need to remember the formula as well.

Key points:
1. Current is the number of coulombs of charge per second.
2. The formula is C/s (Coulomb per second)
3. Current is likened to a flowing river. The larger the current, the more the volume of water is flowing down at any given time. Likewise, the larger the electric current, the larger the amount of charge flowing through a wire at any given time.

4. Voltage is the potential for work to be done.
5. Formula is J/C (Joules per Coulomb)
6. Voltage is likened to tilting a tray of water. When it is not tilted, there is no gravitational potential energy at any point. All have equal gravitational potential energy. When the tray is tilted, the tilted side gains gravitational potential energy and flows to the other side of the tray. Voltage is the same. The dry cell creates a potential difference (like tilting the tray) that enables the electron to flow from one side to the other.

Extra notes:
1. Electron in a dry cell flows from the negative terminal to the positive terminal.
2. There are two types of substances inside a dry cell that creates the potential difference. (refer the video below for more info)


All the best. Post your questions as a comment here.

Cheers,
Teacher Ben

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