The dielectric constant of water is 80, but refractive index

In summary, the conversation discussed the discrepancy between the dielectric constant and refractive index of water, with the conclusion that the two values are measured at different frequencies. The conversation also mentioned that this topic was part of an exam question with four potential options, and the group agreed that option (3) - that the two quantities are measured by different experiments - was the most likely answer.
  • #1
pallab
43
4
The dielectric constant of water is 80, however its refractive index is 1 ·33 invalidating
the expression n*n=ε. why?
 
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  • #2
Dielectric constant and n are frequency dependent. Are you sure you got values at the same frequency?
 
  • #3
Khashishi said:
Dielectric constant and n are frequency dependent. Are you sure you got values at the same frequency?
No.
Actually it is a exam question with 4 options, given below-
(1) the water molecule has no permanent dipole moment
(2) the boiling point of water is 100 °C
(3) the two quantities arc measured by different experiments
(4) water is transparent to visible light

It seems that option (3) is correct .
what do you think?
 
  • #4
This will have to be posted in a homework forum, with the template properly filled out.

Thread closed.
 

FAQ: The dielectric constant of water is 80, but refractive index

What is the relationship between the dielectric constant and refractive index of water?

The dielectric constant and refractive index are both properties that describe how a material interacts with electromagnetic waves. The dielectric constant measures the ability of a material to store and transmit electric charge, while the refractive index measures how much a material can bend light. In the case of water, both properties are closely related and can be affected by factors such as temperature and pressure.

Why is the dielectric constant of water significantly higher than its refractive index?

This is due to the fact that the dielectric constant takes into account the ability of a material to store and transmit electric charge, while the refractive index only measures how much a material can bend light. Water has a high dielectric constant because it is a polar molecule with a strong dipole moment, allowing it to easily store and transmit electric charge. On the other hand, its refractive index is lower because water molecules have a relatively small size and do not cause significant light refraction.

How does the dielectric constant of water change with temperature and pressure?

The dielectric constant of water is affected by both temperature and pressure. In general, as temperature increases, the dielectric constant of water decreases. This is because as water molecules gain more thermal energy, they become more mobile and less able to store and transmit electric charge. On the other hand, increasing the pressure on water can cause an increase in its dielectric constant, as the molecules are forced closer together and become more polarizable.

How does the dielectric constant of water compare to other common substances?

Water has a relatively high dielectric constant compared to most other common substances. For example, the dielectric constant of air is 1, while the dielectric constant of water is 80. This is due to the polar nature of water molecules, which allows them to easily store and transmit electric charge. Other substances with higher dielectric constants than water include polar solvents like ethanol and acetone, which have dielectric constants of 25 and 21, respectively.

What are some practical applications of the dielectric constant and refractive index of water?

The dielectric constant and refractive index of water are important properties in many fields, including chemistry, physics, and engineering. In chemistry, these properties are used to study the behavior of water in different environments and to understand its role in chemical reactions. In physics, they are important in the study of light and electromagnetic waves, and in engineering, they are used in the design of electronic devices and optical instruments. Additionally, the dielectric constant and refractive index of water are important parameters in industries such as food and beverage, cosmetics, and pharmaceuticals, where water is a commonly used solvent.

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