Page 148 - Physics_Form_2

Physics for Secondary Schools

I M Materials: concave mirror, black carbon
i paper, metre rule
r
i P Procedure
C F 1. Hold a concave mirror in such a way
that its reflecting surface faces towards
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the Sun.
R
2. Adjust the position of the concave mirror
Figure 4.22: so that the Sun’s image falls on the piece

For a small aperture of the mirror of carbon paper after reflecting from the
mirror.
around the vertex, 3. Adjust the position of the carbon paper
MF = PF until you find a bright, sharp spot of light
PC = PF CF+ = PF + PF = 2PF on the paper sheet.
R = 2 f 4. Measure the distance between the mirror
R and the paper with the help of the metre
Therefore, f = rule.
2
5. Hold both the mirror and the paper for
Activity 4.7 a few minutes in the same position and
observe what happens.
Aim: To determine the
approximate value of Questions
the radius of curvature What is the length of the radius of curvature
of a concave mirror of the mirror?

What happened to the black carbon paper in step 5? Determining the image location
for curved mirrors is essential when using mirrors for various purposes. Methods
for locating images formed by curved mirrors include the geometrical method and
the mirror formula. The geometrical method involves using ray diagrams, which are
valuable tools for determining the path light takes from the object to our eyes through
the mirror. Figure 4.23 shows the reflection of light rays by curved mirrors.

(a) a concave mirror (b) a convex mirror
Figure 4.23: Ray diagrams for spherical mirrors

142
Student’s Book Form Two

Physics Form 2 Final.indd 142 25/10/2025 10:27