An object is 40 cm to the LEFT of a DIVERGING lens. The MAGNITUDE of the focal l
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Question
An object is 40 cm to the LEFT of a DIVERGING lens. The MAGNITUDE of the focal length of the lens is 20 cm. What is the focal length of the lens?<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
+40 cm
+20 cm
+10 cm
-10 cm
-20 cm
-40 cm
.
10 points
Question 2
For a thin soap film, a light ray moves through air and then into the soap film. It then reflects off the soap-air interface. For this interface,
Answer there is a 180 degree phase change for the reflected ray.
there is no phase change for the reflected ray.
.
10 points
Question 3
On a sunny day you hold a concave mirror outside so that it is illuminated by the intense sunlight. You find that the sunlight focuses to a point
Answer at the center of curvature of the concave mirror.
between the center of curvature and the focal point of the concave mirror.
at the focal point of the concave mirror.
between the focal point and the surface of the mirror.
.
10 points
Question 4
On a bright sunny day you use a magnifying glass of focal length, f, to burn a hole on your Sunday newspaper. When properly focused, the sun (very far away) forms an image
Answer at 2f.
between f and 2f.
at f.
between the lens and f.
.
10 points
Question 5
You observe that a transformer has a primary voltage of 120 V and a secondary voltage of 2400 V. The transformer has 400 secondary turns. How many primary turns to the transformer have?
Answer 8000
60
5
20
.
10 points
Question 6
Q
Answer A.
B.
C.
.
10 points
Question 7
Q7
Answer A.
B.
C.
D.
.
10 points
Question 8
Q1
Answer A.
B.
C.
.
10 points
Question 9
Q6
Answer A.
B.
C.
D.
.
10 points
Question 10
If an ideal gas is compressed isothermally, which of the following statements is true?
Answer Energy is transferred to the gas by heat.
No work is done on the gas.
The temperature of the gas increases.
The internal energy of the gas remains constant.
None of those statements is true.
.
10 points
Question 11
This picture shows an expansion joint at the midpoint of a bridge over the Ohio river. The interpenetrating fingers of the joint are
Answer A. Always the same distance apart at all times of the year.
B. Closer together on the coldest day of the year and farther apart on the hottest day of the year.
C. Farther apart on the coldest day of the year and closer together on the hottest day of the year.
D.
.
10 points
Question 12
A 2.0-mole ideal gas system is maintained at a constant volume of 4.0 liters. If 100 J of thermal energy is transferred to the system, what is the change in the internal energy of the system?
Answer 100 J
400 J
J
0 70 J
Explanation / Answer
1)
p=object distance
q=image distance
f=focal length( negative because diverging lens)
1/p+1/q=1/f
1/40+1/q=1/-20
q=-13.3cm
magnification equation:
M=-q/p
=13.3/40
=.3325
so focal length -40 cm
2)
there is a 180 degree phase change for the reflected ray.
3)
between the center of curvature and the focal point of the concave mirror.
4)
between f and 2f.
5)
60
6)
where is the question
7)
where is the question
8)
where is the question
9)
where is the question
10)
The temperature of the gas increases.
11)
B. Closer together on the coldest day of the year and farther apart on the hottest day of the year.
12)
400 J
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