February 10th, 2018, 10:52 PM  #1 
Newbie Joined: Feb 2018 From: Afghanistan Posts: 17 Thanks: 0  Magnetism
Two parallel straight wires are 1m apart each wire carries a current of 2A in the same direction what is the resultant magnetic field produced by both wires at a point midway between them? Please explain step by step 
February 10th, 2018, 11:37 PM  #2 
Banned Camp Joined: Apr 2017 From: durban Posts: 22 Thanks: 0 Math Focus: Algebra 
try this formula F/L= (μ_0 〖II〗^')/2πr

February 10th, 2018, 11:48 PM  #3 
Banned Camp Joined: Apr 2017 From: durban Posts: 22 Thanks: 0 Math Focus: Algebra 
permit me to ask if the if its stated in the book if the currents are in opposite directions. just to know if they repel each other.
Last edited by Ola Lawson; February 11th, 2018 at 12:12 AM. 
February 11th, 2018, 01:49 AM  #4 
Banned Camp Joined: Apr 2017 From: durban Posts: 22 Thanks: 0 Math Focus: Algebra 
((4π ×〖10〗^(7) t.m/a) (2.00)^2)/(2π)(1.0 x 〖10〗^(3) ) = 4 x 3.14 x 10^7 x 4/ 2 x 3.14 x 0.001 = 5.024 x 10^6/ 6.28 x 10^3 = 5.024/6.28 x 10^6 – (3) = 0.8 x 10 ^3 = 8 x 10^4 n/m 
February 11th, 2018, 02:09 AM  #5 
Banned Camp Joined: Apr 2017 From: durban Posts: 22 Thanks: 0 Math Focus: Algebra 
Parallel wires carrying currents in the same direction attract each other, whereas parallel wires carrying currents in opposite directions repel each other. The magnitude of the force on a length L of either wire is 1. Identify that parallel currents attract each other, and antiparallel currents repel each other. MAJOR REASON WHY AM ASKING IF IT IS STATED THAT THEY ATTRACT EACH OTHER 
February 11th, 2018, 07:24 PM  #6 
Senior Member Joined: Jul 2012 From: DFW Area Posts: 628 Thanks: 92 Math Focus: Electrical Engineering Applications 
I think the answer is 0. Assuming no external fields: Ampere's Law: $\displaystyle \large \oint_l H \cdot dl = \int_S J \cdot ds = I$ For each wire, choose as the surface a circle of radius 0.5m centered on each wire. The line integral is therefore the circumference of the circle. So: $\displaystyle \large H(2 \pi)(0.5)=2$ $\displaystyle \large H \pi = 2$ $\displaystyle \large H=\frac{2}{\pi} \ \left ( \frac{A}{m} \right )$ Imagine the two wires (and currents) coming out of the page with one wire on the right and one on the left. In the middle between the two wires, using the right hand rule, the current of the left wire produces a magnetic field of $\frac{2}{\pi}$ directed upwards while the current of the right wire produces a magnetic field of $\frac{2}{\pi}$ directed downwards. These cancel to give 0 midway between the two wires. 

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