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arango (da2356) – WH01 – markert – (58710)
1
This printout should have 21 questions.
Multiplechoice questions may continue on
the next column or page – fnd all choices
beFore answering.
I posted the Homework a little earlier, so
that you can have a look at it. The Discussion
session will start on Thursday next week and
the due day For the Homework is ±eb 02
001
10.0 points
Diamond has a high index oF reFraction at
about 2
.
4, which helps account For its sparkle.
How Fast does light travel through a dia
mond?
The speed oF light in a vacuum is
3
×
10
8
m
/
s.
Correct answer: 1
.
25
×
10
8
m
/
s.
Explanation:
Let :
n
= 2
.
4
and
c
= 3
×
10
8
m
/
s
.
v
=
c
n
=
3
×
10
8
m
/
s
2
.
4
= 1
.
25
×
10
8
m
/
s
.
The material with the highest index oF reFrac
tion, diamond, will bend light the most.
002
(part 1 oF 2) 10.0 points
Given:
A ray approaching an interFace.
glass
air
What is the approximate reFracted ray?
1.
glass
air
correct
2.
None oF these
3.
glass
air
4.
glass
air
Explanation:
When a light ray goes From glass into air, it
reFracts away From the normal.
003
(part 2 oF 2) 10.0 points
glass
air
What is the approximate reFracted ray?
1.
None oF these
2.
glass
air
correct
3.
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View Full Document arango (da2356) – WH01 – markert – (58710)
2
glass
air
4.
glass
air
Explanation:
When a light ray goes from air into glass, it
refracts toward the normal.
004
(part 1 of 2) 10.0 points
Consider the case in which light ray A is in
cident on
mirror 1
, as shown in the Fgure.
The re±ected ray is incident on
mirror 2
and
subsequently re±ected as ray B. Let the an
gle of incidence (with respect to the normal)
on
mirror 1
be
θ
A
= 56
◦
and the point of
incidence be located 20 cm from the edge of
contact between the two mirrors.
90
◦
x
A
B
mirror 1
mirror 2
θ
A
θ
B
What is the angle of the re±ection of ray B
(with respect to the normal) on
mirror 2
?
Correct answer: 34
◦
.
Explanation:
If the angle of the incident ray A is
θ
A
, the
angle of re±ection must also be
θ
A
. Since the
mirrors are perpendicular to each other, angle
θ
B
is equal to 90
◦

θ
A
θ
B
= 90
◦

θ
A
= 90
◦

56
◦
= 34
◦
.
005
(part 2 of 2) 10.0 points
Determine the angle between the rays A and
B.
1.
56
◦
2.
112
◦
3.
90
◦
4.
0
◦
5.
34
◦
6.
68
◦
7.
180
◦
correct
Explanation:
Refer to the Fgure below.
Consider the
angle each ray makes with
mirror 1
. Ray A
makes an angle of
φ
A
with
mirror 1
. This is
given by
φ
A
= 90
◦

θ
A
=
θ
B
.
The normal to
mirror 2
is parallel to
mirror
1
. Thus the angle ray B makes with
mirror
1
(assumed to be extended) is
θ
B
. Both rays
make the same angle with respect to
mirror
1
. They are parallel, but point in the opposite
directions. Therefore the angle between them
is 180
◦
.
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This note was uploaded on 10/21/2009 for the course PHY 317k taught by Professor Kopp during the Spring '07 term at University of Texas at Austin.
 Spring '07
 KOPP
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