TERM EXAM: SUNDAY DEC 15, 10am-12noon, TC Rexall Centre
All topics since beginning of course
More emphasis on topics post-midterm (65-70%)
Mixed format: mult choice, short answer (more short answer than on midterm)
OFFICE HOURS FOR EXAM: Thur Dec 12, 1:30-2:30pm, or by appointment
1. WHAT’S THE DIFFERENCE BETWEEN FLUORESCENCE & PHOSPHORESCENCE?
o when a UV source that is causing fluorescence is removed, a fluorescent objects stops
glowing, and a phosphorescent one keeps glowing
2. Explain the process for fluorescence
o 3 steps:
o 1. UV photon is absorbed and an e- jumps to a higher level
o 2. e- drops to slightly lower level, and no visible radiation is emitted
o 3. e- returns to the lowest state, it emits a visible wavelength photon
3. What process involves luciferin& luciferase?
o How is bioluminescent emission produced?
chemical reaction involving luciferin, luciferase, and oxygen; this results in the
luciferin being in an excited state (e- is in a high level); when the e- drops to a
lower level, a photon is emitted -> that is bioluminescence (typically blue)
o How does Green fluorescent protein in jellyfish produce green light?
protein absorbs the blue bioluminescent emission; fluorescence occurs, and the
longer wavelength green light is emitted
4. Why do colourless substances absorb UV?
o for the human eye to see a substance with colour, the substance needs to absorb in
the 400-700nm range; when the absorption is in the UV, there is a large energy jump,
and the substance is colorless
5. What sort of molecular structures commonly can absorb in this range and are present on
o eg carotene family: conjugated bonds (alternating double and single bonds)
o eg porphyrins – chlorophyll – extended ring structure, with a heavy metal in the middle
o eg- adding atoms/ atom groups to molecules – Martius yellow
6. What are ionic and colvalent bonds?
7. Why does changing a molecule’s structure change the colour of the substance?
o by changing the structure, the energy level spacing is changed
o the wavelengths that the e- absorbs to jump energy levels changes
o the remaining wavelengths change
o the perceived colour changes
8. What is the law of reflection?
o incoming angle = outgoing angle
9. Define specular and diffuse reflection
10.What is refraction?
o the slowing down and bending of light as it moves from a less dense to a denser
11.What is total internal reflection?
o when a light beam reflects at the interface of 2 mediums instead of refracting and exiting
the medium (see diagram from notes)
12.What is scattering?
o the redirection of a light beam by particles
o Rayleigh: involves small particles that re-direct the shortest wavelengths know why the sky is blue, and why sunsets are red
o Mie: involves larger particles that re-direct all wavelengths – combine to white in