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The post-lab questions provided are SIMILAR to questions you may encounter in your lab manual. These questions will provide you with a step-by-step guide on how we approached the problem. You can use this guide and the data you recorded to help answer the questions. Any given examples with values will be with mock values. Use of these values will almost assuredly give you nonsensical calculations. They are only meant to illustrate the logic.

 

question 1a

You are asked about the source of the light from neon signs.

Understand where the source of the energy is coming from to excite the electrons. These electrons that fall back down to their ground state energy releasing photons.

Remember that the light you see are photons with different colors being the different wavelengths of light. These different wavelengths correspond to different frequencies and energies following c = λv and E = hv.

 

question 1b

You are asked if light source from the flame test is the same as the neon signs asked in question 1a.

Again, think about where the energy source of the neon sign and the energy source of the flame test. Are these the same?

 

Question 2a & 2B

You are asked what the specific part of the spectroscope that separates the light to different wavelengths. The following questions ask where this part is located and for you to draw a sketch.

See the diagram in your lab manual (link) which is similar to the given image. For details, see the overview page (link). Remember to detail in complete sentences and not just one word responses. Points may be deducted from one word responses depending on the TA.

Phenols (click to enlarge)

 

Question 3

Asks you the wavelength from photon emitted from n = 3 to n = 1 by a hydrogen atom.

Since it is hydrogen, you can use the equation given in your lab manual (link). Plug the given values in and solve for the frequency. This frequency can then be used to calculate the wavelength. Remember that the whole number n values should follow n2 > n1

Frequency (v) = R(1/n12 - 1/n22), R = 3.25e15 Hz
Speed of light (c) = Frequency (v) x wavelength (λ) --> c/v = λ

 

Question 4

Asks what color you expect to see from an incandescent lamp if you first put a red and green filter before observing.

Understand that these filters absorb all light except the color of the filter. For example a blue filter will absorb all light EXCEPT the blue light. Use this logic to answer the question.