Relationship Between Conductance and the Dielectric Constant

Click For Summary
SUMMARY

The discussion focuses on the relationship between conductance and the dielectric constant in the context of measuring the dielectric constant of a binary mixture using a parallel plate capacitor. The user is attempting to derive the real part of the dielectric constant (\epsilon') from the conductivity (\sigma) and frequency (\omega) measurements, but is struggling with the equations involved. Key equations mentioned include \kappa=\epsilon'+j\sigma/\omega and C=\kappa\epsilon_{0}\frac{A}{d}. A suggestion was made to utilize impedance from AC voltage and current measurements to derive capacitance.

PREREQUISITES
  • Understanding of dielectric constants and their components
  • Familiarity with parallel plate capacitor equations
  • Knowledge of AC and DC measurements, particularly in relation to impedance
  • Basic concepts of conductivity and its relation to electric fields
NEXT STEPS
  • Research how to calculate impedance from AC voltage and current measurements
  • Learn about the relationship between conductivity and dielectric constant in detail
  • Explore the effects of frequency on dielectric measurements
  • Investigate methods to derive the real part of the dielectric constant from experimental data
USEFUL FOR

Researchers and students in materials science, electrical engineering, and physics, particularly those involved in experimental studies of dielectric properties and capacitive measurements.

AnnaLinnea
Messages
1
Reaction score
0
Hello all,
I'm new to the forum so I hope I'm posting this in the correct section.
I'm currently conducting an experiment in which I'm examining how the dielectric constant of a binary mixture changes with concentration and temperature using a parallel plate capacitor for measurements. The only problem, however is that the multimeter I'm using doesn't measure capacitance. Here's what I can measure:
• DC volts
• AC volts
• DC current
• AC current
• Resistance
• Temperature
• Frequency

My advisor for this project initially suggested that I find the conductance (or conductivity?) in order to calculate the dielectric constant, however I've searched and searched but I can't seem to find a way to relate the two.
Here's what I got so far.
I know that conductivity can be used to calculate the imaginary part of the dielectric constant
\kappa=\epsilon'+j\epsilon''
\kappa=\epsilon'+j\sigma/\omega
where \kappa is the dielectric constant, \sigma is the conductivity and \omega is the frequency.
but I'm not sure how I would find the real part \epsilon'in order to get \kappa
I've also got the equations
C=Q/V
C=\kappa\epsilon_{0}\frac{A}{d} where \epsilon_{0} is the vacuum permittivity, A is the area of the plate and d is the distance between the plates.
Then for conductivity,
J=\sigma E
G=\sigma\frac{A}{d}
where J is the current density and G is the conductance
and so relating the two
C=\kappa\epsilon_{0}\frac{G}{\sigma}
but that still leaves me with two unknowns, C and \kappa
I feel like there's a really simple, really obvious solution that I'm just not seeing...
Can anybody help me out?
 
Physics news on Phys.org
Welcome

Given AC volts and AC current, you can get impedance. From that you can get capacitance.

Is you AC source variable in frequency?
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 36 ·
2
Replies
36
Views
6K
  • · Replies 7 ·
Replies
7
Views
766
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K