Video narration
Does light bounce randomly when it hits a mirror, or can you predict where it will go? I'm Vipul Sir, and let's find out using the mirror you already know. When a light ray strikes a mirror, it comes in and leaves in a reflected direction. Imagine an invisible line at ninety degrees to the mirror, exactly where the ray hits. This is the normal. Now notice the first law: the incoming ray, reflected ray, and normal all lie in the same flat plane. They do not scatter into unrelated directions. The second law gives us the prediction. The angle between the incoming ray and the normal is the angle of incidence. The angle between the reflected ray and the normal is the angle of reflection. These two angles are always equal. So, does a mirror bounce light randomly? No. Use the normal: the angle in equals the angle out, both measured from the normal, and you can predict the reflected ray.