Images of Spherical (Curved) Mirrors
Obj: Observe images and use lens equation with spherical mirrors
Materials: mirrors, meter stick, screen, candle

Methods, Results, and Analysis

A. Focal length of concave (converging) mirror 

1. Arrange the mirror, meter stick, and screen as instructed and sketch. Point the mirror at a distant outdoor object (= infinity) and move the screen along the meter stick until a sharp image appears. Record the focal length (f). Calculate the radius of curvature (C). Estimate the focal length using the “blur” test.

B. Real Images of a concave mirror

1. Place the candle (object) at a distance several cm beyond C. Move the screen until you obtain a sharp image . Record the position (d_o), relative size (h_o), and orientation of the object and image (d_i, h_i). Use the mirror equation to verify the focal length.

2. Place the candle at a distance equal to 2f. Move the screen until you obtain a sharp image. Record the position, size, and orientation of the object and image. Use the mirror equation to verify approximately the focal length. This condition (object at C equals image at C ) is considered the best measurement for the focal length. Compare with f in Part A.

3. Place the candle at a position that is midway between f and C. Move the screen until you obtain a sharp image. Record the position, relative size, and orientation of the object and image. Use the mirror equation to verify approximately the focal length.

C. Virtual Images of a concave mirror

1. Move the candle until it is inside 1f. Try to locate the image on the screen. Observe the image in the mirror. Record the location, relative size, and orientation of the object and image.

D. Convex Mirrors

1. Examine the image in a convex, diverging mirror. How is it similar to and different from a plane mirror and a concave mirror? Explain the phrase on the passenger side mirror of automobiles, “Objects in mirror are closer than they appear.”

---

Back to the Brockport High School Science Department