Finding force between solenoid and magnet

Click For Summary
The discussion focuses on calculating the force between a solenoid and a magnet using the formula F = (μ × n × I² × L) / (2π × r). The permeability of free space is given as μ = 4π × 10^-7 T·m/A, with n calculated as 1333.33 turns per meter based on the solenoid's specifications. The current I is set at 1.85 A, and the length L of the solenoid is 22.619 m, while the radius r is 0.014 m. Participants seek clarification on the origin of the force equation and its specific application in this context. The discussion emphasizes the importance of unit consistency and detailed setup descriptions for accurate calculations.
Mitchell Richardson
Messages
1
Reaction score
0
Homework Statement
I just have a question about finding the force between a solenoid and a magnet at different distances. I have tried using a combination of B=μnI and F=BIL, however the answers I am getting are extremely off from the values that I have measured. Is this equation wrong and if so is there one that achieves what I want?
Relevant Equations
$$B=\mu nI $$
$$F=\frac{BIL}{2 \pi r}$$
$$F=\frac{μn I^{2} L}{ 2 \pi r}$$
$$\mu = 4\pi \times 10^{-7}$$
$$n = \frac{180}{0.135} = 1333.33$$
$$I = 1.85$$
$$L = 22.619$$
$$r = 0.014$$

$$F= \frac{\mu \times 1333.33 \times 1.85^{2} \times 22.619}{2 \pi \times 0.014}$$
 
Physics news on Phys.org
Please describe the set up in detail and provide units with the numbers.
 
Where did you get the second equation? What force is described by it?
 
Thread 'Chain falling out of a horizontal tube onto a table'
My attempt: Initial total M.E = PE of hanging part + PE of part of chain in the tube. I've considered the table as to be at zero of PE. PE of hanging part = ##\frac{1}{2} \frac{m}{l}gh^{2}##. PE of part in the tube = ##\frac{m}{l}(l - h)gh##. Final ME = ##\frac{1}{2}\frac{m}{l}gh^{2}## + ##\frac{1}{2}\frac{m}{l}hv^{2}##. Since Initial ME = Final ME. Therefore, ##\frac{1}{2}\frac{m}{l}hv^{2}## = ##\frac{m}{l}(l-h)gh##. Solving this gives: ## v = \sqrt{2g(l-h)}##. But the answer in the book...

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
Replies
7
Views
1K
  • · Replies 15 ·
Replies
15
Views
1K
  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 12 ·
Replies
12
Views
1K
Replies
25
Views
3K
  • · Replies 3 ·
Replies
3
Views
205
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K