Electric charge of the electron = e = 1.6 x 10 -19 C
Speed of light = c =3 x 10 8 m/s
Mass of the electron = m e
= 9.1 x 10 -31 kg
Planck's constant = h = 6.63 x 10 -34 Js = 4.14 x 10 -15 eVs
Electron volt of energy = 1eV = 1.6 x 10 -19 J
Situation No. Maximum Pts Earned
1
2
3
4
Total
18
27
25
30
100
Bonus 3
Bonus 3
Grand Total
10
20
130

Physics
Name
Light and Optics Hour Exam – Version 1
(3 points for each correct answer, -1 for each wrong answer, then scaled to 18 points max.)
The eye can detect wavelengths that range from 400 nm to 700 nm, where 1 nm = 10
-9
m. The color of this visible light ranges from violet at 400 nm to red at 700 nm. This range closely matches the wavelength range of maximum emission from the
1. The most intense wavelength emitted by the sun is
480 nm. What is the approximate temperature of a blackbody that emits its most intense radiation at the same wavelength?
A. 4,100 K sun.
The relationship between the wavelength of light and the energy of each quantum is
E = hc/
 where h is Planck's constant, c is the speed of light in a vacuum, and

is the wavelength.
Another form of this equation is
E = 1240/
 where

is in nm and E is in eV (electron volts).
Light can be emitted when atoms make transitions from excited states to lower-energy states. Each quantum of emitted light carries energy equal to the difference between the energies of the states involved. For the emitted light to be visible, it is necessary that the states involved be separated by the proper energies. Visible light arises from atomic transitions between energy levels separated by approximately 1.78 to 3.10 eV. For example, assume that the energy levels of a hypothetical atom are the following:
Energy Level 5 -0.8 eV
Energy Level 4 -1.5 eV
Energy Level 3 -4.1 eV
Energy Level 2 -6.3 eV
Energy Level 1 -15.6 eV
Energy will be emitted when an atom makes a transition from a higher to a lower energy level, but visible light will result only when those energies fall within the prescribed range.
Light is also emitted from a hot object by a process called blackbody radiation. The most intense wavelength,
 max
, of blackbody radiation is given by
Wien's displacement law,

  max
= 2.9 x 10
6
/ T, where T is in kelvins and
 max
is in nm.
B. 6,000 K
C. 7,200 K
D. 9,000 K
2. What is the maximum number of emission lines of visible light that could be observed in the spectrum of the hypothetical atom described in the passage?
A. 1 B. 2 C. 5 D. 6
3. A blackbody appears white when its temperature is approximately 6,000 K. Which of the following statements explains the color of light emitted at this temperature?
A. The object is not hot enough to emit red light.
B. The object is too hot to emit blue light.
C. White light is the most common wavelength being emitted.
D. The object is emitting some light from all colors of the visible spectrum.
4. What is the wavelength of the light emitted when the hypothetical atom described in the passage makes a transition from Energy Level 4 to Energy Level 3?
A. 477 nm B. 525 nm C. 600 nm D. 658 nm
5. As the power input to a light bulb decreases, the brightness decreases. How does the color of the emitted light change?
A. The emitted spectrum shifts to longer wavelengths.
B. The emitted spectrum shifts to shorter wavelengths.
C. The most intensive light shifts to lower energy.
D. The spectrum does not change.

Page 2 of 5

Physics
Name
Light and Optics Hour Exam – Version 1
(3 points for each correct answer, -1 for each wrong answer, then scaled to 27 points max.)
Flexible endoscopes are used extensively in medicine to visualize internal structures such as the respiratory tract, stomach, and colon. The advantage of a flexible endoscope over a rigid endoscope is that it can bend and thus go around “corners.” This means less discomfort for the patient and the endoscope can be advanced farther into the cavity of interest.
An endoscope has a number of channels, e.g. for irrigation, suctioning, surgical manipulation, illumination, and imaging. Below is a diagrammatic representation of the imaging components of a relatively simple flexible endoscope.
6.For the best image quality, the following conditions should be met.
A. The core of the fibers must not absorb a significant amount of light.
B. The cladding must have a higher optical density than the core.
C. Light rays must be incident on the core-cladding interface at angles of incidence greater than the critical angle.
D. The endoscope must not be bent too acutely.
7.The critical angle of the corecladding interface is given by
A. critical angle = sin -1 (n cladding
/n core
)
B. critical angle = sin -1 (n core
/n cladding
)
C. critical angle = sin -1 (1/n core
)
D. critical angle = sin -1 (1/n cladding
)
8.If each fiber core is 1 mm in diameter, n core is 1.50, and n cladding is 1.20, what is the minimum length of light-absorbing material required at the ends of the fibers to prevent refraction of light into the cladding?
A. 1 mm
C. 1.5 mm
B. 1.33 mm
D. 2 mm
9. The effect of lens 1 is
A. to possibly reduce overall chromatic aberration
B. to produce a virtual, erect, and diminished image that is the object for lens 2
Lens 1 focal length is -2 cm. Lens 2 focal length is 1 cm. Lens 3 can be easily removed and replaced with another lens. Also, the distance between lens 3 and the end of the optical fibers can be adjusted. Each optical fiber consists of a cylindrical core surrounded by a cladding.
Light enters one end of a fiber and is total internally reflected repeatedly until it exits the fiber at the opposite end.
C. create a wider field of view
D. to invert the image of the object
10.When light has travelled the length of the optical fibers it exits the ends of them and passes through lens 3, which acts like a magnifying glass. If an observer chooses a lens of 50 diopters, how far should lens 3 be from the end of the optical fibers to form an image at infinity?
A. 2.0 cm B. 2.5 cm
C. 3.0 cm D. 3.5 cm
Page 3 of 5

Physics
Name
Light and Optics Hour Exam – Version 1
As a part of your job as an Olympic drug-testing expert, you have been asked to make a judgment on an
Olympic athlete whose body fluid has been given an analysis using a standard spectrophotometer. A calibration curve of the appropriate body fluid was first taken, and then the body fluid of the athlete containing an unknown amount of a possible drug was taken. The data and the curves for both analyses are shown below. wavelength Calibration Unknown nm
375
400
425
450 rel. intensity rel. intensity
0.00
0.00
0.00
0.02
0.00
0.00
0.00
0.01
475
500
525
550
575
600
0.06
0.22
0.64
0.94
1.00
0.77
0.04
0.11
0.19
0.11
0.06
0.06
625
650
675
700
725
0.44
0.16
0.04
0.01
0.00
0.11
0.10
0.03
0.01
0.00
(a) (15 points) You have found from the standard table of concentrations of drugs in this bodily fluid, that the forbidden drug, Neosynepherin, has a maximun absorption at about 575 nm and has an optical density as a function of concentation give by the equation
OD(Neosynepherin) = 3.14 * (concentration of Neosynepherin in gm/liter of body fluid)
Estimate the concentration of Neosynepherin in the body fluid of this athlete. Show your work.
(b) (10 points) It is believed that 200 parts per million of Neosynepherin will enhance the performance of an athlete. Knowing that one liter of body fluid has a mass of 1000 gm, do you think the athlete should be ejected from the Olympic games? Explain your answer.
Bonus points: (10 points) Select an appropriate graph and show the transmission of the body fluid containing the unknown drug as a function of wavelength. Label the axes. Show your work.
Page 4 of 5

Physics
Name
Light and Optics Hour Exam – Version 1
As a part of your job as a health care provider, you have been asked to come up with a plan to help Americans pay for their health care costs. You have been presented with the following data:
The cost of gall bladder surgery in the United States is given below:
Year
1950
Cost
$ 360
1953
1956
1959
1962
$ 412
$ 500
$ 600
$ 702
1965
1968
1971
1974
1977
1980
1983
$ 803* The Medicare Program went into effect in 1966.
$ 1150
$ 1520
$ 2050
$ 2750
$ 3690
$ 4900
From these data, or an appropriate graph, estimate , and explain the process you use to make your estimate
(a) when will gall bladder surgery cost twice as much as it did in 1980? Show your work.
(b) the present annual percentage change in the cost of gall bladder surgery. Show your work.
(c) the cost of gall bladder surgery near the end of your lifetime say, in the year 2053. Show your work.
Bonus (20 points) Select an appropriate graph and show these data as linear function(s). Label the axes.
Page 5 of 5