Name _____________________________
PHYSICS WS
LENSES
Date ______________________________
Period _____________
1.
A student is standing 175 cm away from a CONVEX lens that has a 15.0 cm focal length.
a. How far from the lens is her image? [16.4 cm]
b. If she is 1.65 m tall, how tall is her image? [-0.155 m]
2.
A CONVEX lens has a focal length of 100. cm. A student is standing in front of the lens and notices that
his image on the wall behind the lens has the same height as himself. How far from the lens is the
student standing? [200 cm]
3.
An object is placed 6.0 cm from CONVEX lens of 10.0 cm focal length.
a. What is the image distance? [-15 cm, same side as object]
b. Is the image virtual? [you bet it is!]
c. What is the magnification? [+2.5]
4.
A CONVEX lens (F = 25 cm) is positioned so that its images appear on a screen behind it (lab). A
student (h = 1.70 m) is standing 30.0 m away from the lens.
a. How far from the lens must the screen be placed? [25.0 cm]
b. How tall is her image? [-1.42 cm]
c. The student starts to walk towards the lens. What will happen to the size and distance of her image?
5.
A CONCAVE lens has a focal length of 25 cm. An image is formed 20 cm from the lens.
a. Is the image virtual? [always!]
b. What is the object distance? [100 cm]
c. What will be the magnification of the lens? [+0.20]