Quizlet
Newton's Rings
1. What are coherent sources?
- Two sources that emit light waves of the same frequency with a constant phase difference
- Sources emitting light of different frequencies and random phase
- Two sources emitting unpolarized light
- Sources that reflect light in opposite directions
2. What is interference?
- Absorption of light by a transparent medium
- Refraction of light through a convex lens
- The superposition of coherent waves causing redistribution of energy into constructive and destructive patterns
- The reflection of light at surfaces of different materials
3. Why does a central dark spot appear in Newton's rings?
- Because light is absorbed at the center
- Due to zero thickness at the point of contact and a λ/2 phase change upon reflection, causing destructive interference
- Due to total internal reflection at the contact point
- Because of constructive interference at the center
4. Why are Newton’s rings circular?
- Because the air film between the lens and glass plate is circular and forms loci of constant thickness
- Because of the elliptical curvature of the lens
- Due to light diffraction at the lens edges
- Because of the prism effect of the glass plate
5. How does Newton’s rings pattern change with white light instead of sodium light?
- The rings become sharper and more defined
- It produces colored fringes with a whitish central spot and less distinct rings farther out
- The rings disappear completely
- Only red fringes are visible
6. Why is sodium often considered a single line source despite being a doublet?
- Because D1 and D2 lines have nearly equal wavelengths, producing superimposed rings that appear as from one wavelength
- Because D1 line is too weak to detect
- The spectrometer filters out the D2 line
- Only one line emits visible light
7. What are the approximate wavelengths of sodium D-lines?
- 6120 Å and 6180 Å
- 5000 Å and 5100 Å
- 5461 Å and 5791 Å
- 5890 Å and 5896 Å