-The amount of current flow in a circuit, and therefore the amount of energy transferred to any useful device depends on two things:
1. The potential difference of the power supply (amount of push)
2. the nature of the pathway through the loads that are using the electric potential energy.
-The more difficult the path, the more opposition there is to a flow.
-The measure of the opposition of flow is called electric resistance.
To measure resistance:
R=V/I
where R is the resistance in volts/ ampere (ohm)
V is the potential difference in volts
I is the resulting current in amperes
-A thinner wire has a larger resistance than a thicker one.
-Ohm found that the V/I ratio was constant for a particular resistor. This law is called the Ohm's Law.
-----------------------------------------------------------------------------------------------------------------------------------------
Factors that Affect Resistance
-The longer the conductor, the greater the resistance. Factor: Length
-The larger the thickness of the conductor, the less resistance there is. Factor: Cross-sectional area
-Some materials are better conductors than others. Factor: Type of material
------------------------------------------------------------------------------------------------------------------
Kirchhoff's current law: The total amount of current into a junction point of a circuit equals the total current that flows out of that same junction.
Kirchhoff's voltage law: The total of all electrical potential decreases in any complete circuit loop is equal to any potential increases in that circuit loop.
-In any circuit, there is no net gain or loss of energy or electric charge.
Here are some links I found helpful:
1. http://www.the12volt.com/ohm/ohmslaw.asp
2. http://cnx.org/content/m0015/latest/
3. http://physics.about.com/od/electromagnetics/f/KirchhoffRule.htm
Here is a video for Ohm's Law:
http://www.youtube.com/watch?v=_-jX3dezzMg
and one for Kirchhoff's Law:
http://www.youtube.com/watch?v=Mc_g26ixTtA
No comments:
Post a Comment