A mirror can reflect a covered object if the cover does not completely block the path of light from the object to the mirror and then to your eyes. Seeing an object's reflection isn't about seeing the object directly, but seeing the light that bounces off the object and then off the mirror.
The Principle of Reflection
Mirrors are smooth, flat surfaces designed to reflect light effectively. When light from an object strikes a mirror, it bounces off according to a fundamental rule known as the law of reflection.
As stated in the reference: "Some of the light bouncing off the object will reach the mirror... Since the mirror is a flat, smooth surface, it reflects light at the same angle at which it arrived (also known as the angle of reflection)."
This means the angle at which light hits the mirror (the angle of incidence) is equal to the angle at which it bounces away (the angle of reflection). This precise angle relationship is what allows the mirror to form a clear image of the object – even if you can't see the object itself directly.
Seeing Through the Angles: How a Cover Is Bypassed
When you look in a mirror and see an object's reflection, you are seeing light rays that have traveled in a specific path:
- Light originates from or reflects off the object.
- These light rays travel through space to the mirror.
- The mirror reflects these rays according to the law of reflection.
- The reflected rays travel from the mirror to your eyes.
A cover only prevents you from seeing the object's reflection if it completely blocks either step 2 (light from object reaching the mirror) or step 4 (light from the mirror reaching your eyes).
Consider these scenarios where a cover might be involved:
- Partial Cover: If the cover only hides a portion of the object, light from the uncovered part can still reach the mirror and be reflected.
- Strategic Placement: The cover might be placed directly between your eyes and the object, blocking your direct view. However, light rays traveling from the object at different angles might bypass the cover entirely, hit the mirror, and then reflect towards your eyes, allowing you to see the reflection. The angle of the mirror and your position relative to the object and cover are key factors here.
Essentially, the light doesn't need a direct, straight-line path from the object to your eye if a mirror is involved. It just needs a clear path from the object to the mirror, and from the mirror to your eye. If the cover interrupts only the direct object-to-eye path, the mirror reflection remains visible.
Light Path Breakdown
| Path Segment | Essential for Seeing Reflection? | Can a Cover Block It? |
|---|---|---|
| Object to Mirror | Yes | Yes, if the cover is between the object and the mirror. |
| Mirror Reflection | Yes (governed by angle rule) | No, this is the mirror's function once light arrives. |
| Mirror to Your Eye | Yes | Yes, if the cover is between the mirror and your eye. |
| Object to Your Eye | No (for seeing reflection) | Yes, this is often what the cover is doing effectively. |
In summary, a mirror reflects a covered object by utilizing light that finds a path from the object to the mirror and then to your eyes, even if the cover blocks the direct line of sight to the object itself, adhering to the principle that light reflects at the same angle it arrives.
