November 4th, 2007, 01:38 AM  #1 
Newbie Joined: Nov 2007 Posts: 12 Thanks: 0  Electricity
We know that in a circuit the current through the resistor is the same as the current through the rest of the circuit.But the resistor offers resistance to the flow of current.It retards the flow of current.This being so, how can the current through the resistor be the same as the current through the rest of the circuit. Can anyone give a clear explanation to this problem? Also in a circuit where 2 resistors are connected in parallel why is the potential difference across each resistor the same? 
November 4th, 2007, 03:07 AM  #2 
Newbie Joined: Oct 2007 Posts: 24 Thanks: 0 
In series the current is the same all the way through. Ohm's Law is that Voltage = Current * Resistance so with a constant voltage the higher the resistance the lower the current in the whole circuit. I'm afraid I don't quite understand your second question Hope that helps 
November 4th, 2007, 07:48 AM  #3 
Senior Member Joined: Dec 2006 Posts: 1,111 Thanks: 0 
The short answer to both questions is this: You use voltage division in a series circuit, and current division is a parallel circuit. Let me explain: In a series circuit, voltage drops across each component as you go along, until you reach ground, which has 0 volts of relative potential. Current is not changed. The resistance effects the current, but only in the sense that more total resistance means less total current. The reason that the current does not drop across each resistor is that the current is a function of the TOTAL resistance, and thus putting in a bigger resistor will not cause the current to drop more across that resistor, but will instead cause the current to drop equally through the whole circuit. In a parallel circuit, voltage must still drop across components until it reaches the 0 potential point of ground, but if you have several branches to the circuit, (thus making it parallel) then the same voltage is being applied to each branch. Thus, the same voltage must be dropped across each branch to reach 0 on the other end of each branch, the ends of which are all tied together again at ground. The difference in a parallel circuit is that current, while not changing because of voltage drops, does get split between all the different parallel lines, and as a result, the current is split in direct inverse proportion to the resistances in those lines. If the line has a high resistance, it has a low current, and vice versa. So, in a parallel circuit, resistance does effect the level of current, but in a slightly different way than it would in a series circuit. 

Tags 
electricity 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Fractal Electricity Wave  How to calculate plancks constant  BenFRayfield  Physics  1  August 29th, 2013 07:59 AM 
Working out electricity bill  achtungbaby  Economics  6  September 15th, 2012 05:20 PM 
Help calculate my electricity bill  handbanana  Algebra  4  January 6th, 2009 08:26 AM 