1. Force acting between two long, parallel, current-carrying conductors
© D Hoult 2008

6. Current I2 flows through the field produced by current I1 (and vice versa)

7. Current I2 flows through the field produced by current I1 (and vice versa)
Flux density near conductor 2 produced by I1 is given by

8. Current I2 flows through the field produced by current I1 (and vice versa)
Flux density near conductor 2 produced by I1 is given by
µo I1
B =
2 p r
assuming that the medium is a vacuum (or air)

9. Force acting on a length L of wire 2 is
F = I2 L B

10. Force acting on a length L of wire 2 is
F = I2 L B
Therefore, force per unit length acting on wire 2 is

11. Force acting on a length L of wire 2 is
F = I2 L B
Therefore, force per unit length acting on wire 2 is
µo I1 I2 F = L
2 p r

12. µo I1 I2 F = L
2 p r
1 A is the current which,

13. µo I1 I2 F = L
2 p r
1 A is the current which, when flowing in each of two infinitely long, straight, parallel conductors,

14. µo I1 I2 F = L
2 p r
1 A is the current which, when flowing in each of two infinitely long, straight, parallel conductors, separated by 1m,

15. µo I1 I2 F = L
2 p r
1 A is the current which, when flowing in each of two infinitely long, straight, parallel conductors, separated by 1m, in a vacuum,

16. µo I1 I2 F = L
2 p r
1 A is the current which, when flowing in each of two infinitely long, straight, parallel conductors, separated by 1m, in a vacuum, produces a force per unit length of 2 × 10-7 N m-1

17. µo I1 I2 F = L
2 p r
1 A is the current which, when flowing in each of two infinitely long, straight, parallel conductors, separated by 1m, in a vacuum, produces a force per unit length of 2 × 10-7 N m-1