Why Bubbles of air coming out fish tank appears silvery?

Bubbles of air rising in a fish tank appear silvery due to the phenomenon of total internal reflection. As light from the surroundings strikes the curved surface of a bubble, it undergoes refraction, i.e., bending of light. Depending on the angle at which the light hits the bubble's surface and the refractive index of water and air, the light can undergo total internal reflection.

Total internal reflection occurs when light travelling from a medium with a higher refractive index (in this case, water) strikes a boundary with a medium with a lower refractive index (air) at an angle greater than the critical angle. This causes the light to be completely reflected back into the water, preventing it from escaping the bubble.

As sunlight, which comprises the entire visible spectrum of colours, undergoes total internal reflection inside the bubble, all the colours mix together, resulting in a silvery appearance. Each bubble acts as a miniature mirror, reflecting and scattering the light in all directions, creating the shimmering, sparkly effect observed in fish tanks.

Please note that the specific shades and intensity of the silvery appearance may vary depending on the lighting conditions, water clarity, and size of the bubbles. Some tanks may exhibit more pronounced silvery bubbles compared to others based on these factors.