Biomedical Engineering Reference
In-Depth Information
-33.00 cm
L
= -3.03 D
F
= -10.00 D
n
= 1.00
n
′
= 1.52
+15.00 cm
+3.45 cm
O
I
L
′
= -13.03 D
-11.67 cm
Figure 3-6.
A negative surface produces a virtual image.
size to the object size. It is equal to the ratio of the object vergence to the image
vergence
6
as indicated below:
image size
object size
object vergence
image vergence
M
L
=
=
or simply
L
L
M
L
=
′
In our sample problem, we have
−
2.00 D
M
L
=
= −
0.66
×
+
3.00 D
, the real image is smaller than the
object—it is minified. Negative magnification tells us that the image is inverted.
Since the object height is 3.00 cm, the image height is
(
Because the magnification is less than 1.00
×
−
0.66)(3.00 cm)
= −
1.98 cm
Sample Problem 2: Diverging Surface
An object 15.00 cm in height is located 33.00 cm to the left of a spherical crown
glass surface that has a power of
10.00 D. Locate the image and specify its
magnification. Is the image real or virtual? Is it erect or inverted?
−
As always, first draw a diagram (Fig. 3-6). Since the surface has negative power,
we know that the diverging rays emitted by the object are further diverged by the
6. Lateral magnification is sometimes called
transverse magnification
or
linear magnification.
