Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 36

Negative birefringence occurs under red-compensated polarized light when:

A. Slow light is impeded more than fast light

B. Slow light is less impeded than fast light

C. Fast light runs against the molecular grain of the crystal

D. Both B and C

Step 1 of 2

Negative birefringence:

The word “birefringence” refers to the process of splitting a ray into two parallel rays polarized perpendicularly.

• In crystal polarization, the red-compensation polarized light is positioned between the crystal, and the analyzer

o The compensator divides the light ray into slow-moving, and fast-moving vibrations

• The molecules in monosodium urate (MSU) crystal moves parallel, and when aligning the crystals in slow vibration it produces “yellow” color

o In this process, the velocity of fast light runs against the molecular grain of the crystal, and produces “yellow” color

o This process is considered as “negative birefringence”

Therefore, under the red-compensated polarized, the negative birefringence is occurred when “fast light runs against the molecular grain of the crystal”. Hence, the correct answer is option .