Suppose you want to run some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120 v source has a resistance per unit length of .0065 ohms/m. If your apparatus draws 3.0 A what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
Jenish - drwls, Saturday, February 16, 2008 at 6:42am
The total resistance of the power cord is
95*2*.0065 = 1.11 Ohms. Half of that occurs along one wire and the other along the return wire. (Two wires inside the power cord conduct the current back and forth; many power cords also have a third wire for grounding safety, but the third wire carries no current in proper operation). The total votage drop is V = IR = 3.3 Volts.
The voltage applied to the apparatus will be 120.0 - 3.3 = __ V
Physics to drwls - Jenish, Saturday, February 16, 2008 at 9:10am
Shouldnt we multiply (95/2) by 2 in finding the total resistance.
Jenish - drwls, Saturday, February 16, 2008 at 9:43am
I did multiply 95 m (the cord length) by 2 to get the total length of wire.
<<95*2*.0065 = 1.11 Ohms.>>