Understanding the Effect of Distance on Dipole Behavior: A Scientific Inquiry

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In summary, the video discusses how to treat a system of three charges as a dipole, ignoring the middle charge. This is possible because the distance between the charges is much larger than the size of the charges. The video demonstrates this concept by calculating the contribution from the other two charges, which form a dipole. The net electric field at a point can be found by considering the total field from the middle charge and the dipole. This applies for any value of r, but the condition of r>>a was imposed for simplification purposes.
  • #1
gracy
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in this video from time 1:20 to 1:24

he says we can treat the system of three charges as a dipole ignoring middle charge .I want to know why ?I mean just because r>>a how we can ignore the middle charge ?How is it relevant?
dipole.png
 
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  • #2
From your diagram, it appears you may be getting confused about the charge geometry. In the video, the rightmost charge is positive.
 
  • #3
jedishrfu said:
From your diagram, it appears you may be getting confused about the charge geometry. In the video, the rightmost charge is positive.
No.I know it is positive.
Let me correct it

dipole.png
 
  • #4
In computing the electric field at P, the video considers the middle charge and says it points upward. The rightmost charge points upward and to the left. The leftmost charge the electric field points downward and to the left so if you draw that out you'll be able to find force on P.
 
  • #5
But my question is regarding dipole.
 
  • #6
During the time interval you mentioned, he temporarily omitted the middle charge because he is calculating the contribution from the other two charge, which turns out to form a dipole. You should see toward the end of the video he stated that the net field would be the total field from the middle charge and the dipole.
 
  • #7
blue_leaf77 said:
he stated that the net field would be the total field from the middle charge and the dipole.
yes.But we can consider (the two charges the right most and the leftmost )as a dipole ,right?
 
  • #8
gracy said:
But we can consider (the two charges the right most and the leftmost )as a dipole ,right?
Isn't that what the video demonstrates?
 
  • #9
blue_leaf77 said:
Isn't that what the video demonstrates?
Wanted to verify :smile:
 
  • #10
Yes we can.
 
  • #11
blue_leaf77 said:
Yes we can.
Any conditions for doing that?I mean is it necessary r>>a ?
 
  • #12
No, it applies for any value of ##r##. The condition of ##r>>a## was imposed in order for the expression of the field due to the dipole to be able to be written in terms of ##r##, instead of the distance from the right (or left) most charge to the observation point.
 
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Related to Understanding the Effect of Distance on Dipole Behavior: A Scientific Inquiry

1. What is a dipole?

A dipole is a molecule or compound that has two electrically charged regions, one positive and one negative, due to an uneven distribution of electrons. This results in a separation of charge within the molecule, creating a dipole moment.

2. How is a dipole moment measured?

A dipole moment is measured in units of Debye (D), which is equal to 3.33564 x 10^-30 coulomb-meters (C·m). It is typically measured experimentally using techniques such as spectroscopy or dielectric constant measurements.

3. What is the significance of a molecule having a dipole moment?

A molecule with a dipole moment has a partial positive and negative charge, which can affect its physical and chemical properties. For example, it can impact the molecule's polarity and its ability to interact with other molecules through intermolecular forces.

4. Can a molecule have multiple dipole moments?

Yes, a molecule can have multiple dipole moments if it has multiple polar bonds or if the polar bonds are arranged in a way that does not cancel out the overall dipole moment. This is known as a polyatomic molecule with multiple dipoles.

5. How can a dipole moment be calculated?

A dipole moment can be calculated using the equation μ = Qd, where μ is the dipole moment, Q is the magnitude of the charge, and d is the distance between the charges. It can also be calculated by taking the product of the partial charges and the distance between them in a molecule.

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