PASCO OS-8515C Basic Optics System - Manual (Page 43)

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M o d e l N o . O S - 8 5 1 5 C E x p e r i m e n t 1 4 : V i r t u a l I m a g e s
43
Analysis
The current position of the light source is identical to the previous position of the vir-
tual image.
1. Calculate the virtual image distance d
i1
(the distance between the negative lens
and the virtual image). Remember that it is a negative. Record it in Table 14.1.
2. Calculate the magnification and record it in Table 14.1.
(eq. 14.1)
Questions
1. How do you know that the current position of the light source is identical to the
position of the virtual image when the negative lens was on the bench?
2. In step 5 of the procedure, you predicted the position of the virtual image relative
to the light source. Was your prediction correct?
3. Is M
1
positive or negative? How does this relate to the appearance of the image?
4. Draw a scale diagram showing the light source in its original position, both
lenses, the screen, and both images. Label every part.
5. Draw another diagram at the same scale showing the light source in its final posi-
tion, the positive lens, the screen, and the image.
Part II: Virtual Image Formed by a Convex Mirror
In this part, you will find the location of a virtual image formed by convex mirror.
Procedure
1. Stick a piece of tape to the viewing screen and draw a vertical line on it as shown
in Figure 14.4.
2. Place the half-screen on the bench near one end. Turn the screen so its edge is
vertical (see Figure 14.5).
3. Place the concave/convex mirror on the bench, about 20 cm from the half-screen,
with the convex side facing the half-screen.
Table 14.1: Negative Lens
d
o1
d
i1
M
1
M
1
d
i1
d
o1
--------
⎝ ⎠
⎜ ⎟
⎛ ⎞
– =
Figure 14.4
Figure 14.5