Prof. Williams
3.2.2020
Mirrors, Thin Lenses & Optical Instruments
Purpose: The purpose of this experiment was to demonstrate the following terms like object
distance, image distance, and focal length. We demonstrated that how those term change when we
place an object at different distances from focal length. These terms were observed in spherical
mirrors and curved surface mirrors. We have also observed the properties of the image such as real
image, virtual image, and magnification. We have also observed the properties of optical devices
which they have multiple lenses such as telescope to observe very distant objects.
III. DATA
Concave (Converging) Mirror
f=
15.8 cm
Object Height =
3 cm
Sketch a "Light Ray Diagram" for the first, third and fifth situations above to Scale (create
a reasonable scale):
Object
Image
Image
Image
Description of the Image
Distance (cm) Distance (cm)
Type
Orientatio
n
J
15.85
infinite
The image was at infinity
4f
63.40
21.13
Real
Inverted
Smaller than Obj.
3f
47.54
23.78
Real
Inverted
Smaller than Obj./Bigger than previous
2f
31.70
31.70
Real
Inverted
Same size as the object
1.5
23.78
47.54
Real
Inverted
Image bigger than object
0.5f
7.92
-15.85
Virtual
Same as
Image bigger than object
Obj.
Convex (Converging) Lens
f=
18.85 cm
Object Height =
3 cm_
Object
Image
Image
Image
Size (cm)
Distance
Distance
Type
Orientation
(cm)
(cm)
f
18.859
infinite
4f
75.43
21
Real
Inverted
0.9
3f
56.58
25
Real
Inverted
1.4
2f
37.71
32.5
Real
Inverted
3
1.5
28.28
55.3
Real
Inverted
6.5
0.5f
9.3295
-18
Virtual
Same as
5
Obj.
B.
Telescope
1. Set up a simple telescope using an optics bench with a 300 mm objective lens and 100
mm eyepiece and use it to examine distant objects. Try to estimate the magnification of
this instrument by comparing the view through the lenses with the naked-eye view. Does
this agree with the analysis in the book, in the text Section 34.8?
The image that was seen in the view from telescope was approximately 4X larger than the
object that was seen with naked-eye view. The image was inverted and larger than the
object. The observation agrees with the analysis in the book about the telescope.
2. Investigate the effect of other combinations of lenses. What happens when the 100 mm eyepiece
is replaced by the 50 mm? Comment.
When there was 50 mm instead of 100 mm eyepiece, there was a larger image than the first
procedure.
What happens if the objective lens has shorter focal length than the eyepiece? Comment.
In this case, we would be able to have a full image of parking lot. It can be concluded that with
the objective lens that has a shorter focal length than the eyepiece, there would be smaller
image, which is magnification smaller than 1.
Will the system work with a negative eyepiece (diverging lens)? (Try it). Comment.
The system worked with diverging lens. The image was not inverted because of the -200 lens
which is a diverging lens. The lenses