Calculating Net Force Between Two Dipoles

AI Thread Summary
To calculate the net force between two identical dipoles, each with charge q and separation a, at a distance x apart, one must consider the forces between individual charges in the dipoles. The relevant equation for the force between two charges is Coulomb's law, F = k(q1q2)/r^2. In the limit where a is much smaller than x, the resulting force can be expressed as 6kp^2/x^4, with p representing the dipole moment (p = qa). It is advised to keep the charge as q during calculations and work through the algebra to derive the final expression. Understanding these principles is crucial for solving the problem effectively.
kjintonic
Messages
11
Reaction score
0

Homework Statement


Two identical dipoles, each of charge q and separation a, are a distance x apart, as shown in Fig. By considering forces between pairs of charges in the different dipoles, calculate the net force between the dipoles. Show that, in the limit a<<x, the force has magnitude
6kp^2/x^4, where p=qa is the dipole moment.


Homework Equations


E=2kp/x^3


The Attempt at a Solution


I have no idea where to start T^T
 
Physics news on Phys.org
They say to calculate forces between pairs of individual charges.

Which equation gives the force between two charges?
 
I really don't know... I am a 11th grader and I'm asked to do university stuff;;

oops i forgot the diagram

----- (- +) ---------------------------------(- +)----
--------a--------------------x-----------------a

EDIT: You mean kq1q2/r^2 ??
 
Last edited:
K now I understand that you have to use coulomb's law but how on Earth do i find q of one dipole?
 
Yes, use Coulomb's law.

Just leave the charge as q and work through the algebra.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
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

Can a dipole be modeled as a point charge?
Replies
10
Views
520
Understanding work in translation and rotation of a magnetic dipole
Replies
1
Views
2K
Finding magnitude and direction of net force on a dipole.
Replies
4
Views
7K
Effect of different magnetic fields on a magnetic dipole
Replies
25
Views
1K
Approximating the force on a dipole Taylor series
Replies
3
Views
2K
How Is the Net Force Between Two Dipoles Calculated?
Replies
1
Views
7K
Charge separation of O-H bond in water molecule?
Replies
12
Views
902
Why is a current ring approx a magnetic dipole from very far off?
Replies
7
Views
2K
What is the torque on an electric dipole in an electric field?
Replies
2
Views
2K
Are the 2nd and 3rd problems in this video correctly solved? (charged dipole and organ pipe problems)
Replies
3
Views
1K

Hot Threads

Recent Insights

Back
Top