Page 133 - Physics_Form_2

Nature and reflection of light

to pass through the hole. Observe several rays combine to form a
the ray of light coming through the ‘beam’ of light.
hole.
3. If available, sprinkle some dust or Questions
flour in the air around the light to Focusing on observations in Steps
make the ray more visible. If it is still 2 and 5:
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difficult to see the ray, a thin cloth (a) What insights did you gain from the
or a semitransparent plastic may be
used. observations?
4. Remove the cardboard with a single (b) Highlight the key differences
hole and replace it with another between the two observations.
cardboard piece that has 3-5 small (c) Analyse any patterns in Steps 2 and
holes arranged in a cluster. 5.
5. Shine the flashlight through the (d) What relationships can you identify
multiple holes and observe how between them?

Activity 4.2

Aim: To explore the rectilinear propagation of light
Materials: candle, matches, 3 cardboards of equal size (about 20 cm by 8 cm),
sellotape, string, nail, ruler, screen
Procedure
1. Take three square cardboards of equal size. Locate the centre of each piece of
cardboard by drawing the diagonals.
2. Using a nail, make a hole at the centre of each cardboard.
3. Fix the three cardboards so that they are upright as seen in Figure 4.1.
4. Arrange the cardboards as A, B and C, one behind the other, so that their centres
are in the same horizontal line. You may pass a knitting needle through to confirm
that they are in a straight line.
cardboards

Screen

Light A B C
source

Figure 4.1

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