The concept of unpolarised and polarised light waves and the formulas associated with namely I = Io/ 2 and I =Io cos² q can be best understood if students are allowed to experience and see for themselves :

a) Unpolarised light
b) Polarised light
c) Polarised light going through a polaroid

Polaroid commonly used is purchased through scientific equipment salesman. But these are quite small, usually a pair of 3 cm x 2 cm slide costing RM 80.00 and are rectangular in shape. To use it, a student need to hold the slide or slides very near to his / her eyes for viewing.

This polaroid viewer is much larger, 8 cm in diameter, giving the user a wide range of visuality. In fact where time is limited, a row of 4 to 5 students can view it with the teacher holding it at their eye level.

In addition, rotation to the necessary angles (between polaroid axes) are available allowing students to see the diminishing and increasing intensity of light as the angle between polaroid axes is being gradually increased.

1. To provide opportunities for students to experience on how to prepared their own polaroid viewer.
2. To observed polarised and unpolarised light better.
   
3. To saved times during the experiment because a row of 4 to 5 students can view it together.

1. The students are pleasantly interested to see the diminishing and increasing intensity of light rays as the polaroid are being rotated, as if it is some kind of magic.
2. The students readily accept this 'new technology' differentiating it from ordinary glass or plastic filters.
3. Even though the eventual skills are actually through more explanations, discussions and problem solving, the usage of the polaroid viewer acts as great induction set and convincing tool in encouraging them to accept the abstract concepts of polarised light waves.
4. The students can accept their respective formulas with confidence.
5. At the end of the chapter, most of the students are able to solve STPM questions involving polarised light waves.

The polaroid viewer consists of :

a) Two 8 cm camera polaroid filters
b) One 8 cm diameter PVC pipe - 20 cm long
c) One 8 cm diameter PVC pipe joint

1. One of the polaroid filters is mounted into the PVC pipe using plastic glue to hold the in place.
2. The second polaroid filters is mounted into the PVC joint.
3. Various angles at regular 10° intervals are marked onto the PVC joint.
4. The reference points are marked onto the PVC pipe by obtaining the minimum intensity with both polaroid filters.
5. The reference point is mark to coincide with the 900 angles on the PVC joint.

1. I = I0/2
By observing the intensity of light after going through any one polaroid is enough to convince any student that the formula "may" be true. Actual proof would require experimental data using an intensity meter.

2. I = I0 cos² q
By inserting the PVC pipe into the PVC joint so that light rays going through the two polaroid are observed at one end and then rotating them, students are able to see the gradual :

Diminishing intensity as q goes from 0° to 90°
Increasing intensity as q goes from 90° to 180°
Diminishing intensity as q goes from 180° to 270°
Increasing intensity as q goes from 270° to 360°

3. Confirming the factor cos² q
Actual proof of the formula would require experimental data using an intensity meter.Reflected rays are polarised.

Using any one of the polaroid to view reflected rays from the windowpanes of the classroom, students would be able to see that the reflected rays could be "cut off" by rotating the polaroid to a certain angle (refer 6-P1 and 6-P2).

a) Angles at regular intervals are marked on PVC joint holding the polaroid.
b) A reference point is marked on the PVC pipe holding the other polaroid.

Notice thereduced intensity of light passing through the two polaroids as compared with the background (refer 6-P3)

The polaroid viewer adjusted to a value q = 00 (refer 6-P4).

The intensity of light is only slightly reduced when q = 00 (refer 6-P5).

Notice that the intensity of light is almost zero (refer 6-P6).

The polaroid viewer adjusted to a value q = 900 (refer 6-P7).

It is quite difficult to see the light directly. It would be easier and more effective if a piece of translucent paper is placed inside the PVC joint. The light travelling through the polarizer can be seen on the translucent paper. To compare the light without polarizer and with polarizer, a PVC tube which does not have polarizer and having a translucent paper is placed side by side to the PVC joint. The light falls on the translucent paper can be compared.