Question

Two thin, infinitely long, parallel wires are lying on the ground a distance d=3cm apart. They carry a current I_0=200A going into the page. A third thin, infinitely long wire with mass per unit length lambda=5g/m carries current I going out of the page. What is the value of the current I in amps in this third wire if it is levitated above the first two wires at height h=10cm above them and at a horizontal position midway between them?

Answer 1

Distance between the current I₀ and I is
b=sqrt{0.015²+0.1²} =0.101 m.
According to Bio-Savart Law, the magnetic fields (B₁=B₂) created by the currents lying on the ground at the point where current I is located are
B₁=B₂=μ₀I/2πb =4π•10⁻⁷•200/2π•0.101=
=3.96 •10⁻⁴T.
Net magnetic field is
B₁₂=2B₁cosα,
cosα=0.1/0.101=0.99,
B₁₂=2•3.96 •10⁻⁴•0.99=7.84•10⁻⁴ T.

F=ILB₁₂
mg=λLg

ILB₁₂ = λLg
I= λg/ B₁₂= 0.005•9.8/7.84•10⁻⁴=
=62.5 A

Answer 2

So did this work out Lora?

Answer 3

Hi, Colin
When I saw this, I was out of attempt. I don't know this is correct or not but I got mine wrong. Did you solve angle theta hinge one question?

Answer 4

not yet

Answer 5

yup got green check ans is 62.5A thx Elena!

Answer 6

hai @Elena
plz help m on this question ?????

An infinitely long wire carries a current I=100A. Below the wire a rod of length L=10cm is forced to move at a constant speed v=5m/s along horizontal conducting rails. The rod and rails form a conducting loop. The rod has resistance of R=0.4ohms. The rails have neglibible resistance. The rod and rails are a distance a=10mm from the wire and in its non-uniform magnetic field as shown. What is the magnitude of the emf induced in the loop in volts?

Answer 7

PLEASE!! anyone has a hint on the question posted by @klaus???

By the way, any idea on:
A square loop of wire of side L with total resistance R moves at constant speed v into a region of uniform magnetic field B pointing perpendicular to the plane of the loop. What is the average current that is induced. ???