Loop is a circle:
Loop is a "wavy circle":
If Loop carries unit of electric current, what is the magnetic flux through Loop ?
Details and Assumptions:
1)
Magnetic permeability
2)
This link
may be helpful (hyperphysics website)
3)
Give your answer as a positive number
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Consider a point on loop 1:
r 1 = ( 3 + cos θ 1 ) i ^ + ( 2 + sin θ 1 ) j ^ + 0 k ^
And that on loop 2:
r 2 = cos θ 2 i ^ + sin θ 2 j ^ + ( 5 + 5 sin θ 2 ) k ^
The arc length elements on each loop can be computed by evaluating the total differentials:
d r 1 = ( − sin θ 1 i ^ + cos θ 1 j ^ + 0 k ^ ) d θ 1 d r 2 = ( − sin θ 2 i ^ + cos θ 2 j ^ + 5 cos θ 2 k ^ ) d θ 2
Finally, we can compute the elementary magnetic vector potential at any general point due to loop 1:
d A = 4 π μ o I ( ∣ r − r 1 ∣ d r 1 )
The total magnetic potential vector due to loop at any point can be evaluated as such:
A = 4 π μ o I ∮ L 1 ∣ r − r 1 ∣ d r 1
Now, we know that the magnetic field at that point can be computed as such:
B = ∇ × A
The elementary surface area through the loop is say: d S . This means that elementary flux is:
d Φ = B ⋅ d S
The total flux can be computed by integrating over the surface area of loop 2 as such:
Φ = ∮ S 2 B ⋅ d S ⟹ Φ = ∮ S 2 ( ∇ × A ) ⋅ d S
Applying Stoke's theorem leads to:
Φ = ∮ S 2 ( ∇ × A ) ⋅ d S = ∮ L 2 A ⋅ d r 2 Φ = ∮ L 2 ∮ L 1 4 π μ o I ∣ r 2 − r 1 ∣ d r 1 ⋅ d r 2
Substituting expressions and simplifying the integrand gives a function f ( θ 1 , θ 2 ) and the integral looks as such:
Φ = ∫ 0 2 π ∫ 0 2 π f ( θ 1 , θ 2 ) d θ 1 d θ 2
I performed this entire calculation process using a script of code and have only provided an outline. The answer evaluates to:
Φ ≈ 0 . 0 1 7