Cracking the SAT Physics Subject Test

Here’s How to Crack It

31. With so = 48 cm and f = −24 cm, the lens equation gives us:

The image is 16 cm from the lens, on the same side as the

object.

32. Because si is negative, the image is virtual.


33. Virtual images are upright.


34. The magnification is

(The fact that the magnification is positive confirms that the

image is upright.) The height of the image is

hi = |m| • ho = (9 cm) = 3 cm

These results are illustrated in Question 25.