This document contains a midterm exam for a 3rd year Biomedical Engineering course. It includes the following: 1) Multiple choice questions about types of spectra, materials used for optics, and fluorescence emission. 2) Drawings of the relative intensity curves for different optical filters: a neutral density filter, glass filter, and interference filter. 3) A diagram and explanation of the parts of an optical two-mirror Ebert monochromator design. 4) A calculation problem to determine the characteristic wavelengths of absorption, emission, and fluorescence spectra for a hydrogen-like atom excited by a specific wavelength range, illustrated with an energy level diagram.

1. Cairo University 3rd year Biomedical Eng. Nov. 2011
Faculty of Eng. Mid Term Exam-Analytical Instrumentation Time : 60 Min
(1)Choose the correct answer:
a- High pressure mercury vapor lamp can be considered as a source of the following type of spectra:
Visible spectra Infra red yellow line spectra U.V. spectra
b - Quartz is used as an optical material in the range:
UV +Visible Visible + near IR Visible up to far IR U.V.+ Visible+ near IR
c - Fluorescence spectra radiates when atomic energy transition from energy level En to energy level Em
where:
En < Em En > Em and m>1 En not equal to Em En < Em and n> 1
e - The wavelength at which the maximum emissive power of the radiated spectra from an oven occurs
at λ = 1172 nm, its temperature is:
3500 0
k 2000 0
k 5500 0
k 4000 0
k
(2)Draw the relative output intensity curve for the following filters:
Neutral density filter
(Transmittance = 0.8)
Glass filter (=450 nm) Interference filter
n=1.37 , t=275 nm
Intensity
input
1.0

Intensity
input
1.0

Intensity
input
1.0


2. (3) Draw a clear diagram showing each part of the optical design of the two-mirror Ebert
mounting monochromator. State the function of each its parts.

3. (4) The ionization potential energy of an hydrogen like atom is 54.4 ev. If it is excited by a beam of
wavelength 23.6<λ<24.2 , find the characteristic wavelengths of the resulting :
(a) Absorption, (b) Emission, and (c) Fluorescent spectra.
Illustrate your answer by an energy level diagram.
( Electron charge = -1.6 x 10-19
C , speed of light in vacuum = 3 x 108
m/sec ,
Planck’s constant = 6.63 x 10-34
Joule.sec)