Define the Ampere: Force/Length = 2*10-7N/m

  • Thread starter Thread starter pat666
  • Start date Start date
  • Tags Tags
    Ampere
AI Thread Summary
The discussion focuses on defining the ampere through the interaction of two parallel wires carrying current. When the wires are 1 meter apart and carry equal currents, they experience a force of 2 x 10^-7 N, which establishes the current as 1 ampere. The expression for force per unit length is derived as F/length = μ₀I²/2πd. The user seeks clarification on how to simplify their equation, specifically regarding the term I². Understanding this relationship is crucial for accurately defining the ampere in the context of electromagnetic theory.
pat666
Messages
703
Reaction score
0

Homework Statement


Two very long, thin, straight, parallel wires each carrying a current I in the same direction are separated by a distance, d. With the aid of a diagram which indicates the current directions, account for the force on each wire and show on the diagram the direction of one of the forces. Write an expression for the magnitude of the force per unit length of wire and hence define the ampere.


Homework Equations





The Attempt at a Solution


did necessary steps to get to force/length=uoI2/2pi*d
then at 1m separation F=2*10-7I2
From text: "if two long parallel wires 1m apart carry equal currents and experience a force of of 2*10-7N then the current is defined to be 1Ampere"
I think I am pretty close to the answer but I have a force of 2*10-7I2 -how do I get rid of the I2?
 
Physics news on Phys.org
You are defining the Ampere, so I= 1 A.
 
thanks I thought it would be something simple like that...
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Ampere definition and infinite wires separated by 1 meter
Replies
8
Views
2K
Correct usage of Ampère's law for calculating B-field outside parallel wires?
Replies
4
Views
1K
What is the net force on the current loop?
Replies
8
Views
2K
Magnetic force on a wire due to a loop
Replies
1
Views
1K
Multiple choice Q: Mangetic fields and Spring Constant
Replies
8
Views
2K
Forces of a straight wire on a semi-circular wire loop (Magnetism)
Replies
17
Views
3K
Problem involving Ampere's Law and Understanding
Replies
4
Views
3K
Defining Ampere: Length of Wire Explained
Replies
20
Views
3K
Find the Retarding Force due to Eddy Currents
Replies
5
Views
1K
Magnetic Force Between Current-Carrying Wires
Replies
2
Views
9K

Hot Threads

Recent Insights

Back
Top