Allan Hancock College
Physics 153 Lab
Lenses and Mirrors
Purpose:
The purpose of this lab is to observe the laws of reflection and refraction as
applied to lenses and mirrors.
Apparatus:
Optical bench, lens and mirror holders, various lenses and mirrors.
Procedures:
Mirror Experiments
1) Plane mirror: Place an object in front of a plane mirror. Have one lab
partner hold the plane mirror, while another measures the distance that the
object is from the mirror and its height. Then while one partner observes the
image in the mirror another partner measures the image distance.
For plane mirrors, theory states that h’ = h, and |q| = p. Compare your
measured h’ and q with the theoretical values. What are reasonable
estimates of uncertainty with your measurements?
2) Concave and convex mirrors: Qualitatively explore the images produced for
each mirror. Start with the mirror at one end of the optical bench. Place an
object (arrow) in a holder directly in front of the mirror. Observe the image
as you gradually move the object away from the mirror. Describe your
results.
Lens Experiments
1) Place a lens holder with a converging lens on the optical bench. Allow light
from a distant source to fall on the lens. Place a screen on the opposite side
of the lens and slowly move the screen closer to the lens until the image of
the object comes into focus.
Measure the image distance. If p ~ infinity, then q = f.
Is the image real or virtual? Is it erect or inverted?
2) Now take a light source and place it on one side of the converging lens,
with the screen on the other. Place the light source a distance p > f and
gradually move the screen until the image comes into focus. Measure the
object and image distances and calculate the f. How does this compare with
the focal length that you got before? How does it compare with the
manufacturer’s advertised focal length? Is the image real or virtual?
3) Place the light source a distance p < f and look through the converging lens
from the opposite side. Where does the light source appear to you?
Measure the actual and apparent distance of the source (p and q). How
does the image distance compare with theory? Is the image real or virtual?
4) Place a lens holder with a diverging lens on the optical bench. Place the
light source a distance p from the lens and look through the lens from the
opposite side. Where does the light source appear to you? Measure the
actual and apparent distance of the source (p and q), and calculate f. How
does this compare with the manufacturer’s advertised focal length. Is the
image real or virtual?