AIIMS 2004
- Exam
- AIIMS
- Year
- 2004
- Subject
- Physics
- Chapter
- Wave Optics
AIIMS 2004 · Physics · Wave Optics
Assertion : At the first glance, the top surface of the Morpho...
Assertion : At the first glance, the top surface of the Morpho butterfly's wing appears a beautiful blue-green. If the wing moves the colour changes.
Reason : Different pigments in the wing reflect light at different angles.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion
- BIf both assertion and reason are true but reason is not the correct explanation of assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false
Step-by-step solution
Many Morpho butterflies are coloured in metallic, shimmering shades of blue and green. These colours are not due to pigmentation but due to iridescence: the extremely fine lamellated scales covering the Morpho's wings reflect incident light repeatedly at successive layers leading to interference effect that depends on both the wavelengths and angle of incidence. Thus the colours produced vary with viewing angle. However they are actually surprisingly uniform, perhaps due to the tetrahedral (diamondlike) structural arrangement of scales or diffraction from overlying cell layers. This structure may be called photonic crystal.