Question

A mineral of uniform composition is cut into a wedge shape. The birefringence of the wedge section is 0.012. The retardation at 40 µm thickness of the wedge is ________ nm. \text{[in integer]}

Hint:

Retardation is calculated by multiplying the birefringence of the material by the thickness of the sample.

Answer 1

Correct Answer: 480

The retardation \( \Delta \) is given by the formula:
\[ \Delta = \text{birefringence} \times \text{thickness} \] Substituting the given values: \[ \Delta = 0.012 \times 40 \, \mu\text{m} = 0.012 \times 40 \times 10^{-6} \, \text{m} = 480 \times 10^{-9} \, \text{m} = 480 \, \text{nm} \] Thus, the retardation at 40 µm thickness is \( \boxed{480} \, \text{nm} \).