# Calculating Torque and Frequency of a Polar Molecule

• besnik93
In summary, the conversation discusses a simple model of a polar molecule consisting of a rod with two charges at each end. The molecule is placed between two capacitor plates and can experience a torque when rotated away from its equilibrium position. The conversation also mentions calculating the torque and frequency of small oscillations around the equilibrium position. There is some confusion about how to express the force on the charges and the equilibrium position being at the center of mass of the rod.
besnik93

## Homework Statement

A simple model of a polar molecule is a rod of length L with mass m where the charges q
and -q is arranged at each end of the rod. The molecule is located between two capacitorplates where spacing is on potential difference between the capacitor is V. The molecule will have a
equilibrium position (apart from gravity), but when the molecule is rotated away from the angle θ
equilibrium position will be affected by a torque τ.

a) Calculate the torque τ. Calculate the frequency f at which the molecule can perform small oscillations around the equilibrium position

## The Attempt at a Solution

I think of using the force on the charges which is the charge * electric field strength, but i don't know how to express that, can someone help please

If I am illustrating this correctly then this should have a couple moment applied to the "rod"?

The wording on this is a bit confusing, and if there a screenshot to go along with this, so we can all be on the same page?

I can't take a screenshot, but how to calculate a torque of these charges and this rod.

Well look at the force on your charges due to the magnetic field contained within the capacitor and recognize you'd have two equivalent moments directed in opposite directions at all times, which is a couple.

The equilibrium position is going to be at your center of mass of the rod it looks like.

How do i express that to make sense, i am really confused

## 1. What is torque and frequency of a polar molecule?

Torque is a measure of the twisting force that is applied to an object. In the case of a polar molecule, it refers to the twisting force that is exerted on the molecule due to the presence of an electric dipole moment. Frequency, on the other hand, refers to the number of times the molecule oscillates or rotates in a given time period.

## 2. How is torque calculated for a polar molecule?

The torque exerted on a polar molecule can be calculated by multiplying the electric dipole moment of the molecule by the electric field strength it is exposed to. This can be expressed as T = μE, where T is the torque, μ is the electric dipole moment, and E is the electric field strength.

## 3. What factors affect the torque and frequency of a polar molecule?

The torque and frequency of a polar molecule are primarily affected by the strength of the electric field it is exposed to, as well as the size and orientation of its electric dipole moment. Additionally, the molecular mass and shape can also play a role in determining the torque and frequency.

## 4. How does temperature affect the torque and frequency of a polar molecule?

At higher temperatures, the molecules in a substance have more kinetic energy and tend to vibrate and rotate more. This can cause an increase in the torque and frequency of polar molecules as they are exposed to more collisions and interactions with other molecules.

## 5. Can the torque and frequency of a polar molecule be measured experimentally?

Yes, the torque and frequency of a polar molecule can be measured experimentally using techniques such as Raman spectroscopy or microwave spectroscopy. These methods involve exposing the molecule to specific wavelengths of light or microwave radiation and measuring the resulting changes in its rotational or vibrational energy levels.

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