Question

15. What are positive and negative crystals​

Answer 1

Answer:

(optics) a doubly refracting crystal in which the index of refraction for the extraordinary ray is greater than for the ordinary ray, and the former is refracted nearer to the axis than the latter, such as as quartz and ice; as opposed to negative crystal: one in which this characteristic is reversed, such as Iceland.

Explanation:

What is negative crystal?

• 1 : a cavity that has the form of a crystal and occurs in a mineral mass. 2 : a crystal showing negative double refraction.
• What are positive and negative crystals give examples?
• Negative uniaxial crystals (e.g. calcite CaCO3, ruby Al2O3) have ne < no so for these crystals, the extraordinary axis (optic axis) is the fast axis whereas for positive uniaxial crystals (e.g. quartz SiO2, sellaite (magnesium fluoride) MgF2, rutile TiO2), ne > n o and thus the extraordinary axis (optic axis) is the ...

Answer 2

Answer:

Here are the meanings of Positive crystals and negative crystals.

Explanation:

Any solid material in which the component atoms are arranged in a specific pattern and whose surface regularity mirrors its internal symmetry is referred to as a crystal. Any solid material in which the component atoms are arranged in a specific pattern and whose surface regularity mirrors its internal symmetry is referred to as a crystal.

Positive crystals

A doubly refracting crystal in which the index of refraction for the extraordinary ray is greater than the index of refraction for the ordinary ray, and the former is refracted closer to the axis than the latter, such as quartz and ice; as opposed to a negative crystal, which has the opposite characteristic, such as Iceland spar or tourmaline.

Negative crystals

A uniaxial, birefringent crystal, such as calcite or ruby, in which the extraordinary ray's velocity exceeds that of the ordinary ray. This can alternatively be characterised as the extraordinary axis' index of refraction, ne, being less than the ordinary axis' index of refraction, no, making the extraordinary axis the fast axis of these crystals.

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