Finding magnitude of torque on a molecule

In summary, molecules of carbon monoxide are permanent electric dipoles with a horizontal axis and a vertical electric field of strength 15000 N/C. The net force on the molecule is zero, and the magnitude of the torque on the molecule is 5.6*10^-27. The maximum torque on a dipole equals the force on one charge times the distance between them. When finding the force on each molecule, one must multiply by the distance instead of dividing by the radius squared.
  • #1
catan
5
0

Homework Statement



Molecules of carbon monoxide are permanent electric dipoles due to unequal sharing of electrons between the carbon and oxygen atoms. The figure shows the distance and charges. Suppose a carbon monoxide molecule with a horizontal axis is in a vertical electric field of strength 15000 N/C.

The picture they provide is one of 2 circles connected together in a linear line with C on the left and O on the right. The diagram shows them to be .11 nm apart from each other. The C has a +3.4E-21 charge and the O has a -3.4E-21 charge.

A. What is the magnitude of the net force on the molecule?

B. What is the magnitude of the torque on the molecule?


Homework Equations


F = eE
Torque = qEL


The Attempt at a Solution



Ok, so part A I got right. I just used the F = eE equation and got the answer 2.4E-15 and thought that I would be using this for part B.

In part B my book shows the equation qEL = torque. It says that qE is the magnitude of the electric force and L is the length they are from each other.

Torque = (2.4E-15 N) * (1.1E-10 m) = 2.64 E -25

This isn't right though. What am I doing wrong? I really appreciate the help!
 
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  • #2
catan said:
Ok, so part A I got right. I just used the F = eE equation and got the answer 2.4E-15 and thought that I would be using this for part B.
Is the electric field uniform? I don't understand how you got your answer for the net force on the molecule. (What's the net charge on the molecule?)
 
  • #3
Oh wait, I just realized the answer to part A is zero because they cancel each other out. I was wrong. So the torque tho I'm supposed to use not the net force but the force on the individual atoms? 3.4E-21

I'm still lost...
 
  • #4
The maximum torque on a dipole equals the force on one charge times the distance between them. Read about it here: http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/diptor.html"
 
Last edited by a moderator:
  • #5
to find the force on each molecule, you divided by the radius squared. don't do that - multiply by the distance instead--traditonally torque is distance * force

so it is 15000 * 3.4*10^-21 * .11*10^-9 = 5.6*10^-27
 

Related to Finding magnitude of torque on a molecule

1. How is torque on a molecule defined?

The torque on a molecule is a measure of the twisting force or rotational force acting on the molecule. It is defined as the product of the force applied on the molecule and the perpendicular distance from the axis of rotation to the point where the force is applied.

2. What factors affect the magnitude of torque on a molecule?

The magnitude of torque on a molecule is affected by the applied force, the distance from the axis of rotation, and the angle at which the force is applied. Additionally, the shape and orientation of the molecule also play a role in determining the magnitude of torque.

3. How is the magnitude of torque on a molecule calculated?

The magnitude of torque on a molecule can be calculated using the equation τ = F x r x sinθ, where τ is the torque, F is the applied force, r is the distance from the axis of rotation, and θ is the angle between the force and the lever arm.

4. Why is it important to determine the magnitude of torque on a molecule?

Determining the magnitude of torque on a molecule is important in understanding the structural stability and physical properties of the molecule. It can also provide insights into the molecule's behavior and interactions with other molecules.

5. Can the magnitude of torque on a molecule be negative?

Yes, the magnitude of torque on a molecule can be negative. This means that the direction of the torque is opposite to the direction of the rotational motion. A negative torque can also result in a net decrease in the molecule's rotational speed.

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