The Law Of Reflection. Measuring the angle of incidence and angle of reflection.

The video introduces the law of reflection: the angle of incidence is equal to the angle of reflection. The presenter will demonstrate this and show how to measure these angles. Equipment includes a light box (12 volts), a lens to adjust the light beam, and a plain mirror to reflect the light. A plastic piece with thin slits is used to narrow the light beam for more accurate measurements. A paper protractor is used for measuring angles.

The video explains that the reflected ray of light changes angle as the mirror is moved. The law of reflection the angle of incidence equals the angle of reflection is the focus. An imaginary line called the 'normal' is introduced; it is 90 degrees to the surface of the mirror and is the reference point for measuring angles. When the incident ray comes along the normal (0 degrees incident angle), the reflected ray also travels back along the normal (0 degrees reflected angle).

The presenter moves the light source so the incident ray is at a 10-degree angle from the normal. The reflected ray is also observed to be at a 10-degree angle from the normal, confirming the law of reflection.

The light source is moved further, setting the angle of incidence to 30 degrees. The angle of reflection is also measured at 30 degrees, again verifying the law.

With the incident ray at 50 degrees from the normal, the reflected ray is also at 50 degrees, providing another example of the law.

The incident ray is set at a wide angle of 80 degrees from the normal. The reflected ray also measures 80 degrees, consistently confirming the law of reflection across various angles. The importance of measuring angles from the normal is emphasized.

The video then experiments with a curved mirror, specifically the concave side (curved inwards). Moving the mirror shows how the incident ray hits at different points, causing the reflected ray to change angles. Interesting shapes like triangles and right angles can be formed due to light traveling in a straight line.

Finally, the convex side (curved outwards) of the mirror is used. The presenter demonstrates how the light reflects differently from this curved surface, highlighting the fun in experimenting with curved mirrors.