TECHNICAL&MECHANICAL
Sunday, November 8, 2015
Monday, October 19, 2015
OHM'S LAW
1. Ohm's Law deals with the relationship between voltage and current in an ideal conductor. This relationship states that:
The potential difference (voltage) across an ideal conductor is proportional to the current through it.
The constant of proportionality is called the "resistance", R.
Ohm's Law is given by:
- V = I R
- I = g V

4. An increase of potential energy in a circuit causes a charge to move from a lower to a higher potential (ie. voltage). Note the difference betweenpotential energy and potential.
Because of the electrostatic force, which tries to move a positive charge from a higher to a lower potential, there must be another 'force' to move charge from a lower potential to a higher inside the battery. This so-called force is called the electromotive force, or emf. The SI unit for the emf is a volt (and thus this is not really a force, despite its name). We will use a script E, the symbol
, to represent the emf.

A decrease of potential energy can occur by various means. For example, heat lost in a circuit due to some electrical resistance could be one source of energy drop.



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