Biomedical Engineering Reference
In-Depth Information
Now let's calculate the lateral magnification. From Chapter 3, recall that
L
L
M
L
=
′
Therefore,
−
1.25 D
M
L
=
+
4.75 D
M
L
= −
0.26
×
The image is minified and inverted. Its size is
(
1.30 cm
As with lenses, we can also calculate magnification using linear distances. But
because the light rays reverse direction after reflection, we must insert a minus sign
into the equation:
−
0.26) (5.00 cm)
= −
′
−
l
M
L
=
l
For our example, we have
−2
1.05 cm
M
L
= −
−
80.00 cm
M
L
= −
0.26
×
For this same mirror, locate the image if the object is located 10.0 cm in front of the
mirror. Is the image real or virtual? Is it erect or inverted? What is the magnification?
Before performing any calculations, it's helpful to note that the object is located
within the focal distance (
f
16.67 cm). As is the case for a con-
verging lens, this results in an image that is virtual, erect, and magnified.
The object vergence is
1
l
′
=
−
100/6.00 D
=
−
=
L
1
=
L
−
0.10 cm
= −
10.00 D
The image vergence is determined with the paraxial equation
L
L
′
=
L
+
F
L
′
= −
10.00 D
+
6.00 D
L
′
= −
4.00 D
