Page 185 - Physics_Form_2

Refraction and dispersion of light
Activity 5.7
Aim: To determine the angle of
minimum deviation of an
equilateral triangular glass
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prism
Materials: a white sheet of paper,
a drawing board, an
equilateral triangular
glass prism, drawing pins,
a metre rule, a pencil,
office pins, graph paper,
i−r +e−r +180°− D = 180° a protractor, ICT Tools
m
(computer or tablet with
graphing software, digital
camera, simulation tool)
Procedure
1. Place the white sheet of paper on
the drawing board and fix it with the
help of drawing pins.
2. Place an equilateral glass prism on
top of the paper and trace its outline.
3. Remove the prism and label the
outline as ABC.
4. On the side AC just above the centre
of the outline, draw a perpendicular
line NQ.
5. Measure the angle of incidence of
25° at the point of the perpendicular
line and draw a line RQ.
6. Insert two pins P and P on the line
1
2
RQ and replace the glass prism.
Physics Form 2 Final.indd 179
7. On the other side of a prism, trace
the pins P and P which appear to
3
4
be in line with P and P , and draw
2
1
line TS as shown in Figure 5.15.
Figure 5.15
8. Extend line RQ and line TS with
dotted lines to meet at a point M.
9. Measure the angle of deviation D.
10. Repeat steps 5 to 8 for other angles
of incidence of 30°, 35°, 40°, 45°,
50°, 55° and 60°.
11. Record your results in a table similar
to Table 5.3.
12. Use ICT tools or otherwise to;
(a) input your recorded data into
a graphing software, if ICT is
used. If not, start at (ii)
(b) create a graph of the angle of
deviation (y-axis) against an
angle of incidence (x-axis)
(c) find the angle of minimum
deviation, which corresponds
to the lowest point on the graph.
13. Optionally, capture images of your
experimental setup and results to
document your process.
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