Work of the Ampère force and parallel currents
Answers are for parents and teachers.
1
I = 10 A and ΔΦ = 30 mWb. What is the work in mJ?
300
2
l = 40 cm, B = 0.25 T (perpendicular), I = 5 A; the conductor moves 20 cm. What is the work in mJ?
100
3
Two parallel wires carry I₁ = I₂ = 20 A, d = 4 cm. What is F/Δl in mN/m?
2
4
Why are the forces that two parallel currents exert on each other equal in size (Newton's third law)?
Each current lies in the field of the other and the expression μ₀I₁I₂Δl/(2πd) is symmetric; the forces are an action–reaction pair.
5
If the source is disconnected (no current), is work done on the conductor by the magnetic force?
No: without current there is no Ampère force (F = I·B·l = 0).