13.2.2. Activity 13.2

Perform Activity 13.1 again. This time use a sheet of stiff paper or a chart paper. Let the sheet project a little beyond the edge of the Table (Fig. 13.4). Cut the projecting portion of the sheet in the middle. Look at the reflected ray. Make sure that the reflected ray extends to the projected portion of the paper. Bend that part of the projected portion on which the reflected ray falls.

Can you still see the reflected ray? Bring the paper back to the original position. Can you see the reflected ray again? What do you infer?

In this part of the activity, students are asked to recreate the previous light reflection experiment using stiff paper or chart paper. By having part of the paper extended beyond the table edge, they create a scenario where they can manipulate the visibility of the reflected ray. When they bend the paper, they effectively change the angle and orientation of the surface that the light ray is reflecting off of, which allows them to observe the changes in visibility of the reflected ray. The underlying inference is about the importance of the orientation of reflective surfaces when it comes to observable light.

Imagine you're wearing a hat while looking in a mirror; if you tilt your head or move your hat up or down, the reflection in the mirror changes. Similarly, just like the paper bending changes how we see the light reflecting, positioning objects at different angles can alter what is seen in mirror reflections.

Measure the angle of incidence and the angle of reflection. Repeat the activity several times by changing the angle of incidence. Enter the data in Table 13.1.

This portion emphasizes the practical understanding of the angles involved in reflection. Students are instructed to measure the angle at which the incoming light (incident ray) strikes the surface compared to the angle at which it reflects away. By modifying the angle of incidence during multiple trials, students gather data to reinforce the concept that these angles are equal according to the law of reflection. This experimentation helps solidify their understanding of how light behaves upon striking reflective surfaces.

Think of throwing a basketball against a wall. If you throw it at a sharp angle, it bounces off at the same angle on the other side. The relationship between the angle you throw it (angle of incidence) and where it lands (angle of reflection) is similar to what happens with light reflecting off surfaces.

When the whole sheet of paper is spread on the table, it represents one plane. The incident ray, the normal at the point of incidence and the reflected ray are all in this plane. When you bend the paper you create a plane different from the plane in which the incident ray and the normal lie. Then you do not see the reflected ray. What does it indicate? It indicates that the incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane. This is another law of reflection.

This part of the activity explains an essential law of reflection, emphasizing the importance of planes in reflection. When the paper is flat, all angles are aligned, allowing for clear reflection. However, when the paper is bent, the three components involved - the incident ray, the normal, and the reflected ray - no longer lie within the same plane, resulting in no visible reflection. This observation reinforces the understanding that proper alignment is crucial for reflection to occur.

Imagine a road with traffic signals and cars. If all the cars (light rays) are aligned straight, everything functions smoothly; everyone sees the green light (reflected light). If one car swerves off to the side (the bending of the paper), other drivers (the reflected rays) can no longer see the signal properly, emphasizing the necessity of alignment.

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