Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Notifications
Mark all as read
Q&A

Why do markers reflect light, even when the light source fails to illumine the space between the source and markers?

+0
−3

Please see below screenshot of 15:59.The LED spot light (fastened to the front of the boat) illumines merely a few meters in front, and fails to illumine most of the water between the boat and the markers. So how can the LED still illumine the markers that I highlighted in orange?

It counters intuition that although a light fails to illumine the area between the source and the target, the light can still illumine SOLELY the target! Please correct my intuition?

I never studied science after secondary school. Please explain like I am (1)5.

Image alt text

Why does this post require moderator attention?
You might want to add some details to your flag.
Why should this post be closed?

1 comment thread

x-post https://www.reddit.com/r/explainlikeimfive/comments/uazi31/eli5_why_do_markers_reflect_light_e... (1 comment)

1 answer

You are accessing this answer with a direct link, so it's being shown above all other answers regardless of its score. You can return to the normal view.

+2
−0
It counters intuition that although a light fails to illumine the area between the source and the target, the light can still illumine SOLELY the target!

The light is illuminating everything. The photons don't magically disintegrate some fixed distance from the light source. The illumination gets smoothly dimmer with distance. At some distance, the light is dim enough so that it appears to your eyes like there is no illumination.

Your question doesn't explain what these "markers" are, so I'll assume they are buoys put there specifically to be visible. In that case, they most likely have areas with retro-reflective paint on them. The point of retro-reflective paint is to reflect light in about the same direction it came from. That means a high percentage of the light from your lamp that hits these markers is bounced back into your eyes. This is certainly not true of the water, which will reflect most light away from you.

The markers are reflecting many times more of the light that hits them from your lamp than the water does. As a result, they look brighter to your eyes than the water does.

Why does this post require moderator attention?
You might want to add some details to your flag.

0 comment threads

Sign up to answer this question »

This community is part of the Codidact network. We have other communities too — take a look!

You can also join us in chat!

Want to advertise this community? Use our templates!

Like what we're doing? Support us! Donate