Page 172 - Physics_Form_2
P. 172
Physics for Secondary Schools
tracing the ray of light as it leaves Materials: plain paper, soft board,
the glass block. drawing pins, transparent
4. Remove the glass block and draw glass block, protractor
a line joining points M and N.
Observe the direction of the line Procedure
MN as compared to the line drawn 1. Place a plain paper on a soft board.
FOR ONLINE READING ONLY
in Step 2. Fix the paper firmly on the board
using drawing pins.
Ray box Normal line 2. Place a rectangular glass block on
the paper and trace its outline. Draw
a line perpendicular to the outline of
Air the glass block. This is the normal
line.
M 3. Draw a light ray that meets the side
of a glass block such that it makes
Glass block a small angle with the normal line.
This is the angle of incidence (i).
Mark the meeting point as M.
N 4. Stick two pins, P1 and P2 along the
Air light ray drawn in step 3.
5. Observe the pins through the block
Figure 5.4 from the opposite side.
6. Stick two other pins, P3 and P4,
Question so that they appear in line with P1
Is there any change in the direction of and P2.
the ray of light as it emerges from the 7. Draw a line joining the points of
other side of the glass block? Explain. the two pins and the edge of the
glass block at point N as shown in
There is a change in the direction of light Figure 5.5.
when it passes from air to glass (first 8. Remove the glass block and draw a
boundary) and when it passes from glass line, MN, joining point M and point N.
to air (second boundary). This is because 9. Draw a line perpendicular to the
light is passing through different materials outline of the glass block at point
with different optical densities. N. This is also a normal line.
10. Measure the angle between the
normal line and the refracted ray.
Activity 5.3 This is the angle of refraction (r).
Aim: To measure the angles of Note: Both the angle of incidence and
incidence and refraction the angle of refraction are measured
using a glass prism from the normal line.
166
Student’s Book Form Two
Physics Form 2 Final.indd 166 25/10/2025 10:27
