How to ensure an equation is dimensionless when it includes "Debye"

In summary, the conversation discusses how to determine if an expression is dimensionless and how to deal with a (Debye^2) term. It is explained that the cgs-unit for the electric dipole moment is dimensionless, and the Debye term can be simplified to equal 1. The individual expresses gratitude and offers credit to @vanhees71 for their help.
  • #1
bumblebee77
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Can anyone please help me figure out how to break down "Debye" into base units so that I can check if an expression is dimensionless in the CGS system?
I am trying to check if an expression is dimensionless. If it is, then I have done things correctly. However, I am stuck on how to deal with a (Debye^2) term. How can I break it down to find out if it cancels out with the other units I have left? I know this is probably a trivial question, but just cannot figure it out.

I have this ("^2" means "squared"):

(Debye^2) (s^2) / (cm^5) g
 
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  • #2
An expression is of course dimensionless in any system of units. It's the cgs-unit for the electric dipole moment having the dimension Franklin times cm. Now ##1 \text{Fr} =1 \text{statC}=1 \sqrt{\text{g} \; \text{cm}^3/\text{s}^2}##. So ##\text{Debye}^2 \text{s}^2/(\text{cm}^5 \text{g})=1 \text{g} \; \text{cm}^5/(\text{cm}^5 \; \text{g})=1## 👍
 
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  • #3
vanhees71 said:
An expression is of course dimensionless in any system of units. It's the cgs-unit for the electric dipole moment having the dimension Franklin times cm. Now ##1 \text{Fr} =1 \text{statC}=1 \sqrt{\text{g} \; \text{cm}^3/\text{s}^2}##. So ##\text{Debye}^2 \text{s}^2/(\text{cm}^5 \text{g})=1 \text{g} \; \text{cm}^5/(\text{cm}^5 \; \text{g})=1## 👍
@vanhees71, thank you so much. I just could not get my head around this. Really appreciate it. I voted you up and if there's any other way I can give you credit, just let me know.
 
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FAQ: How to ensure an equation is dimensionless when it includes "Debye"

How do I determine if an equation is dimensionless?

To determine if an equation is dimensionless, you need to check the units of each term in the equation. If all the units cancel out and you are left with a unitless number, then the equation is dimensionless.

What is the significance of including "Debye" in an equation?

"Debye" is a unit used to measure electric dipole moment. Including it in an equation indicates that the equation is related to electric dipole moments and their interactions.

How can I ensure an equation is dimensionless when it includes "Debye"?

To ensure an equation is dimensionless when it includes "Debye," you need to make sure that all terms with units of "Debye" cancel out and you are left with a unitless number. This may involve converting other units to "Debye" units or simplifying the equation algebraically.

Can an equation be dimensionless without including "Debye"?

Yes, an equation can be dimensionless without including "Debye." The presence of "Debye" simply indicates that the equation is related to electric dipole moments, but there are other ways to create a dimensionless equation without using this unit.

Why is it important for an equation to be dimensionless?

Having a dimensionless equation allows for easier comparison and analysis of different physical quantities. It also helps to simplify calculations and make them more generalizable to different systems and units of measurement.

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