Tuesday, September 14, 2010

Resistance, Ohm's Law, and Kirchhoff's Laws

The amount of energy transferred to any device depends on two things:
1. The potential difference of the power supply.
2. The nature of the pathway through the loads that use the electric potential energy.

The amount of current flowing through a resistor changes depending on the amount of energy that's put in the resistor.


A thin wire will have more resistance, while a larger one will have less.
In order to calculate resistance, we use the formula R=V/I. Where R is the resistance in ohms (Ω), V is the potential difference in volts and I is the current in amperes.

The ratio between Voltage against Current is constant and is known as Ohm's Law.

Kirchhoff's Current Law: The total amount of current into a junction point equals the total current that flows out of the same point.


Kirchhoff's Voltage Law: The total of all electric potential decreases in any complete circuit loop is equal to any potential increases in that circuit loop.
 
Kirchhoff's laws apply to the laws conservation of electric charge and the conservation of energy. To make it short, in any circuit, there is no net gain or loss of electric charge or energy.

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