SNC 2D Lab: Locating Images in Concave Mirrors

Purpose: To use ray diagrams to predict the characteristics of the image from a concave mirror and to test your prediction. To apply the use of concave and convex mirrors to everyday life applications.

Pre-Lab Activity: Finding the Focus and Centre of Curvature

Take a mirror and stand at the side of the room. Locate the image of the window and measure the distance from the mirror to the image. This is the focus. Record below.

Mirror Number: ______Focus: ______cm

Centre of Curvature = 2 x the focus = ______cm

Materials:

meter stickconcave mirrormirror holdercandle

candle holderscreen

Predictions:

Use ray diagrams drawn to scale to predict the characteristics of the image of the flame in each of the situations below. Complete this on a separate sheet of paper.

  • Scale 1.0 cm on the drawing = 4.0 cm in real life
  • Represent the flame by an arrow that is 0.5 cm tall.
  • Only 2 rays are necessary, but you may add more

Summarize your results in the table.

Table 2: Predicted Properties of the Flame Image

Object Location / Object Location from mirror (cm)
You choose this / Size of Image
( Height in cm) / Attitude of Image / Location of Image from mirror
(cm) / Type of Image
Beyond C
At C
Between C and F
At F
Closer than F
(Inside F)

Have your teacher check your predictions. ______(signature)

Observations:

Use the meter-stick-optical-bench set-up to test your predictions.

  1. Put the candle at the location you chose for “Beyond C”.
  2. Light the candle.
  3. Move the screen until you have found the image of the flame.
  4. Record the properties of the image in the table below.
  5. Move the candle to the next location and repeat.

Table 2: Observed Properties of the Flame Image

Height of Flame: ______cm

Object Location / Object Location from mirror
(cm) / Size of Image (Height in cm) / Attitude of Image / Location of Image from mirror (cm) / Type of Image
Beyond C
At C
Between C and F / (not too close to F)
At F
Closer than F / (not too close to the mirror)

Analyzing Results

  1. In general, how accurate were your predictions? Which ones were good? Why do you think this is? Which ones were inaccurate? Why do you think this is? Use your predicted data and your quantitative measurements directly in your answer.
  1. Where, in general, must the object be located for a concave mirror to produce a real image? Support your answer with your predictions and your lab data.
  1. What happens to the size of the real image as the object is slowly moved from beyond C towards the mirror? Support your answer with your predictions and your lab data.
  1. What is the only location where a converging (concave) mirror will not produce any image at all? Did your lab results support this? Explain.
  1. Where must an object be located in order for a concave mirror to produce a virtual image?

Communication Rubric for Ray diagrams /5

  • Mirror drawn in correctly (reflective side facing object, correct shape chosen)
  • Principle Axis (PA), Centre of Curvature (C), Focus (F) , and Vertex (V) labeled
  • C and F at the correct distance from the mirror
  • Object drawn at the correct location from mirror
  • Used a ruler to draw light rays
  • Light rays have arrows that represent the correct direction of light path
  • Light rays in front of the mirror are drawn as solid lines
  • Light rays behind the mirror are drawn as dashed lines
  • Location of image is within reasonable error
  • Characteristics of image represented on diagram (Size, Attitude, Location, Type)
  • Diagram is scaled correctly

Communication Rubric for Written Component/5

  • Information & ideas communicated with high degree of clarity and precision; main idea is very clear
  • Communication is fluent & appropriately reworded
  • Vocabulary is appropriate to the content and used in the correct context
  • Information is detailed and accurate
  • Includes interpretations that demonstrate understanding of content/skills
  • Used appropriate examples/data to support explanation