Download Sample Midterm 1

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KOÇ UNIVERSITY
SCIENCE 106
FASCINATING WORLD OF LIGHT
Alphan Sennaroğlu
MIDTERM EXAM 1
Maximum Score = 100 points
Time allowed = 75 minutes
Closed-book Exam
NOTE ON ACADEMIC INTEGRITY
Academic dishonesty, in particular, cheating during the examination, will not be
tolerated and disciplinary action will be taken against those involved.
DIRECTIONS
1) PLEASE CHECK TO MAKE SURE YOUR EXAM BOOKLET HAS 5 PAGES.
2) PART 1:
3) CALCULATORS ARE ALLOWED.
NAME: _____________________________________________________________
DEPARTMENT:_____________
SIGNATURE:_______________________
PART 1 (32 POINTS):______
PART 2 (40 POINTS):______
PART 3 (28 POINTS):______
TOTAL SCORE :
______
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PART 1: SHORT-ANSWER QUESTIONS (32 POINTS)
Question 1: (6 points)
A ray of light passes from air into a transparent plastic at oblique incidence as shown below. If the index of
refraction is 1.5, calculate sinand give the name of the law you used to do the calculation.
air
600
plastic

Question 2: (8 points)
Below are shown two spherical rain drops. Sketch the path of sun rays inside the drops that will give rise
to primary and secondary rainbows. Clearly label the blue and red rays separately.
Primary (3 pts)
secondary (5 pts)
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Question 3: (4 points)
The figure below shows the path of light traveling from air into water. Mark the air side and the water side
of the interface.
interface
Question 4: (6 points)
How many times can light go around the earth in one second? Take the circumference of the earth as
40,000 km and c=3x108 m/s.
Question 5: (8 points)
Name 4 of Newton’s major contributions to science. It is sufficient to describe each contribution in one
sentence.
1.____________________________________________________________________________________
______________________________________________________________________________________
2.____________________________________________________________________________________
______________________________________________________________________________________
3.____________________________________________________________________________________
______________________________________________________________________________________
4.____________________________________________________________________________________
______________________________________________________________________________________
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PART 2: MULTIPLE-CHOICE QUESTIONS (40 POINTS) (Each question is worth 4 points)
1) (4 pts) Which of the following is correct about Nicholaas Bloembergen?
(a) He developed the wave theory of light.
(b) He proposed the model of the solar system in which the Sun is at the center with the planets moving in
elliptical orbits.
(c) He showed that at the surface of nonlinear materials, the angle of incidence may not be equal to the
angle of reflection at high light intensities.
(d) He lived in the 17th century during Newton’s times.
2) (4 pts) Two Polaroid sheets are placed as shown below, with the arrows indicating the direction of
alignment of the molecules. In which configuration will the region of overlap of the polaroids transmit the
least amount of light?
(a)
(c)
(b)
(d)
450
3) (4 pts) The index of refraction between air and a special plastic is 2. Hence, the critical angle for total
internal reflection will be
(a) 25
(b) 30 (c) 48
(d) 42 degrees
4) (4 pts) The index of refraction for air-glass interface is 1.5. As light goes from air to glass,
(a) the angle of incidence and the angle of refraction are equal.
(b) the angle of incidence is greater than the angle of refraction.
(c) the angle of incidence is less than the angle of refraction.
(d) total reflection will occur if the angle of incidence in air is larger than 42 degrees.
5) (4 pts) Which of the following is correct about total reflection?
(a) total reflection occurs when the incidence angle is above the critical angle.
(b) total reflection occurs when the incidence angle is below the critical angle.
(c) the interface must be coated by a metal such as aluminum or gold in order to reflect back all of the light.
(d) the critical angle is the same for all pairs of materials.
6) (4 pts) Which of the following is correct about fiber optics?
(a) Metallic wires are used to transmit light by total reflection.
(b) Light can be guided over long distances even if the angle of incidence is less than the critical angle.
(c) Optical fibers are not suitable for transmitting light over kilometers of distance.
(d) Glass wires are used to transmit light by total reflection.
7) (4 pts) Which of the following is correct about Olaus Roemer’s measurement of the speed of light?
(a) He determined the speed of light from the irregularities in the occurrence times of the eclipses of
Jupiter.
(b) Roemer showed that light travels faster in air than in water.
(c) He used a fast rotating mirror to measure the speed of light.
(d) He determined the speed of light from the irregularities in the occurrence times of the eclipses of
Jupiter’s moon Io.
8) (4 pts) All of the following are in agreement with Newton’s theory of light except:
(a) light beams intersect without any interaction because light particles are tiny.
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(b) light moves in a straight line because the light particles move so fast that gravity does not bend them
down significantly.
(c) light moves more slowly in water than in air.
(d) the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.
9) (4 pts) According to Newton’s theory of refraction, at oblique incidence near the interface between air
and water,
(a) the parallel component of the particle velocity remains the same in air and water.
(b) the parallel component of the particle velocity increases in water.
(c) the perpendicular component of the velocity remains the same in air and water.
(d) the perpendicular component of the velocity decreases in water.
10) (4 pts) According to Newton’s law of gravitation,
(a) the gravitational force between two objects could be repulsive or attractive.
(b) the gravitational force between two objects is constant as a function of distance.
(c) the gravitational force between two objects varies inversely as the square of the distance.
(d) the gravitational force between two objects varies inversely as the product of the masses.
PART 3: TRUE/FALSE (28 POINTS) (Each question is worth 2 points)
1)___In a single uniform medium, a light ray moves in a straight line.
2)___According to Snell’s law, the angle of refraction is linearly proportional to the angle of incidence.
3) ___At the glass-air interface, the critical angle for red color is the same as the critical angle for the blue
color.
4) ___The fact that light travels with a finite speed was discovered much later than Newton in the
nineteenth century.
5) ___ In glass, the index of refraction is the same for all colors.
6) ___The order of the colors is reversed in the secondary rainbow compared to those of the primary
rainbow.
7) ___Leon Foucault did the first comparative measurement of the speed of light in air and water.
8) ___According to Newton, red and blue colors are deviated by different amounts because particles of red
color are more massive than the particles of blue color.
9) ___According to Newton, light consists of tiny particles that obey the classical laws of motion like
baseballs.
10) ___Newton proved that different laws of motion are needed to explain terrestrial and celestial motions.
11) ___By using his law of gravitation, Newton showed that planets followed elliptical orbits.
12)___Newton’s particle theory of light is still accepted and widely used in science today.
13) ___In order to enhance the colors of a brilliant gemstone, the lower facets are cut at a special angle to
cause total reflection of incident light.
14)___The secondary rainbow appears above the primary rainbow in the sky.
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Table of Sines (sines are given up to 2 decimal places)
theta
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
sin
(theta)
0.00
0.09
0.17
0.26
0.34
0.42
0.50
0.57
0.64
0.71
0.77
0.82
0.87
0.91
0.94
0.97
0.98
1.00
1.00
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