Magnetic forces on two current carrying wires

AI Thread Summary
To find the force per unit length on two parallel wires carrying different currents, the magnetic field generated by one wire is used to calculate the force on the other. The correct formula for the force per unit length is F/L = (μ₀ * I₁ * I₂) / (2π * d), where d is the distance between the wires. For the given currents of 2.0 A and 4.0 A at a distance of 0.24 m, the total force per unit length is 6.7 * 10^-6 N/m, indicating an attractive force. The initial calculations incorrectly treated the magnetic field contributions from each wire separately, leading to confusion about differing forces. The final consensus confirms that the forces are indeed equal and attractive, despite the different currents.
endeavor
Messages
174
Reaction score
0
"Find the force per unit length on each of two long, straight, parallel wires that are 24 cm apart when one carries a current of 2.0 A and the other a current of 4.0 A in the same direction."

Tell me if I'm doing this right:
I use d = 0.24m, and the equations B = (mag. perm. * I)/(2*pi*d), and F = ILB.

The force per unit length on each wire is then: F/L = IB.

Plugging in I and B for each of the wires, I get:
F/L (for the 2.0A wire) = 3.3 * 10^-6 N/m (toward the other wire)
F/L (for the 4.0A wire) = 1.3 * 10^-5 N/m (toward the other wire)

I think it's wrong because the answer is supposedly: "6.7 * 10^-6 N/m; attractive". But I would think that the forces are different on each wire, because the wires are carrying different currents...
 
Physics news on Phys.org
Your formulae are correct, however I can't see how you obtained your two different answers.
Remember, the expression you wrote explicitly is
\frac{\mu_0I_1I_2}{2\pi d}

Can you possibly have two different answers ? :)
 
oh ooops.
I did (F/L)1 = I1B1, not I1B2!
 
Thought so :biggrin:
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Calculating Magnetic Field at Point P for Perpendicular Current-Carrying Wires
Replies
2
Views
1K
Electromagnetism question -- Forces between two current carrying wires
Replies
7
Views
3K
Force on rectangular loop by a current in a long straight wire
Replies
4
Views
2K
What is the net force on the current loop?
Replies
8
Views
2K
Magnets near a current carrying wire
Replies
12
Views
2K
Magnetic Forces on infinite current-carrying wires
Replies
9
Views
2K
Why is magnetic field B along a straight wire circular not radial?
Replies
14
Views
3K
How Does a Magnetic Field Affect a Wire Carrying Current?
Replies
2
Views
1K
Forces of a straight wire on a semi-circular wire loop (Magnetism)
Replies
17
Views
3K
Calculation of torque and force on magnetic dipole near infinite wire
Replies
3
Views
1K

Hot Threads

Recent Insights

Back
Top