Light Absorption, Reflection, and Transmission

Light Interaction with Matter
📌 When light moves from one medium to another (e.g., air to a gummy bear), three primary interactions occur: reflection, absorption, or transmission.
💡 Reflection is when light bounces off the surface, where the angle of incidence always equals the angle of reflection ($\theta_i = \theta_r$).
🔥 Absorption occurs when light energy is converted into another form of energy, usually heat.
💨 Transmission means the light passes through the medium, sometimes resulting in refraction (discussed later).

Color and Energy Absorption
🟢 Objects display color based on which wavelengths of light are reflected versus absorbed; for instance, a leaf appears green because it reflects green light and absorbs red and blue light.
🔬 Chlorophyll A and B pigments in leaves absorb heavily in the bluish-purplish and reddish-yellow light spectrums, while transmitting or reflecting the green light.
☀️ Some plants have evolved reddish or bluish barriers on the underside of leaves to reflect energy back up, maximizing light absorption for photosynthesis.

Gummy Bear Experiment Observations
🔴 In the demonstration using a green laser on colored gummy bears, most light was transmitted, with some reflection off the surface and significant absorption, as seen by the red gummy bear absorbing the green light.
🔍 The amount of reflection, absorption, and transmission observed depends directly on the pigments and chemicals present within the medium (the gummy bears).

Key Points & Insights
➡️ When light reflects off a surface, the angle of incidence equals the angle of reflection.
➡️ The color we see from an object is the light that is reflected; all other visible wavelengths hitting that object are generally absorbed (and converted to heat).
➡️ Understanding light interaction is crucial for explaining phenomena like seeing an image of a mountain reflected in a lake, which is due entirely to reflection.

📸 Video summarized with SummaryTube.com on Feb 25, 2026, 07:26 UTC