Question

Sometimes when looking at a window, you see two reflected images slightly displaced from each other. What causes this?

Short answer

The reflection from both inner and outer surface of the glass causes two reflected images slightly displaced from each other.

Step-by-step solution

Definition of Reflection of Light

When a light beam strikes a smooth surface, it bounces back in the same medium. This phenomenon is called reflection of light.

Double reflection

As the light from the glass of the window reflect from the inner face as well as the outer face of the glass window, and the glass window have some thickness, which makes the reflected images shifted.

Hence, the two reflected images get slightly displaced from each other.