Underwater Lightbulb Optical Illusion - Reflection/Refraction of Light

[physicsgator]

Homework Statement

"Provide a true explanation for what you see as you look at a lightbulb underwater"

(See the attached Image)

What you see:
Out of water -> white opaque light bulb
Underwater -> clear outside, opaque white inside

Homework Equations

N/A

The Attempt at a Solution

I think this has something to do with refraction of light and the index of refraction of the coating of the lightbulb.

Thanks for you help!

 

[ptr]

The refraction of light from water to a curved glass then to air might cause the glass of the light bulb to look thicker. An optically opaque coating has no index of refraction of meaning, and is not part of the explanation.

 

[thomate1]

I can provide a true explanation for what you see when looking at a lightbulb underwater. This phenomenon is due to the principles of reflection and refraction of light. When light travels from one medium to another, such as from air to water, it changes speed and direction. This change in direction is known as refraction. The angle of refraction depends on the difference in the refractive indices of the two media. In this case, the refractive index of air is lower than that of water, causing the light to bend as it enters the water.

Now, when we look at the lightbulb underwater, we are seeing the light that is reflected and refracted by the water and the lightbulb itself. The clear outside of the bulb allows light to pass through it without much distortion, while the opaque white inside reflects and scatters the light, making it appear white. This creates the illusion of a clear outside and a white inside when viewed underwater.

Additionally, the coating on the lightbulb plays a role in this illusion. The coating has a higher refractive index than the glass of the bulb, causing more refraction and making the outside of the bulb appear clearer than the inside.

In conclusion, the underwater lightbulb optical illusion is a result of the reflection and refraction of light as it passes through the water and the lightbulb, and the difference in refractive indices between the two media. This phenomenon is a great example of how the properties of light can create fascinating illusions.