Optical Phenomena

Understanding everyday optical phenomena and why we see what we see

Topics

How do fiber optics work?

Fiber optics work by using total internal reflection to guide light through thin glass or plastic fibers. Light entering the fiber at angles greater than the critical angle reflects off the fiber walls, bouncing along the fiber without escaping. This allows light signals to travel long distances with minimal loss.

How do LED lights work?

LED (Light Emitting Diode) lights work by electroluminescence—when electric current flows through a semiconductor diode, electrons recombine with electron holes, releasing energy as photons (light). The semiconductor material determines the light color, and LEDs are highly efficient, converting most electrical energy into light.

How do mirrors create reflections?

Mirrors create reflections by having smooth, polished surfaces that bounce light back. When light hits a mirror, it reflects at the same angle it arrived (angle of incidence equals angle of reflection), creating clear, organized reflections that form images.

How do sunglasses work?

Sunglasses work by reducing the amount of light reaching your eyes through tinting (absorbing light) and often polarization (filtering specific light orientations). They protect eyes from bright light, reduce glare, and block harmful UV radiation.

Why do objects appear smaller in the distance?

Objects appear smaller in the distance due to perspective—the visual angle they subtend decreases with distance. As objects move farther away, they occupy a smaller angle in our field of view, making them appear smaller. This is a geometric effect of how light rays from distant objects reach our eyes.

Why do shadows form?

Shadows form because light travels in straight lines and cannot pass through opaque objects. When an object blocks light, it creates a dark region (shadow) where light cannot reach. The shadow's size and shape depend on the light source and object position.

Why do we see colors in soap bubbles?

We see colors in soap bubbles because of thin-film interference. Light reflects from both the front and back surfaces of the bubble film, and these reflections interfere. Different wavelengths interfere constructively or destructively at different film thicknesses, creating the colorful patterns we see.

Why do we see mirages?

We see mirages because hot air near the ground has different density than cooler air above, causing light to refract (bend). This creates the illusion of water or objects appearing where they don't exist, with the image often appearing inverted or distorted.

Why do we see stars twinkle?

Stars twinkle (scintillate) because of atmospheric turbulence. As starlight passes through Earth's atmosphere, it encounters varying air densities and temperatures that refract light. These rapid changes in refraction cause the star's apparent position and brightness to fluctuate, creating the twinkling effect.

Why do we see the moon during the day?

We see the moon during the day because the moon reflects sunlight, and when the moon is in the right position relative to the Sun and Earth, it's bright enough to be visible against the bright daytime sky. The moon is always in the sky about half the time, but we notice it more when it's visible during the day.