SPM Physics AmalI-Apparent Depth & Reflection: What Happens When You Put a Glass Block on Text?

 

This photo was not originally planned as an experiment.

After completing my glass block practical in the Physics laboratory, an idea suddenly came to mind.

I placed the glass block directly on top of one of my AHA! Physics Posters and took this photo.

The result was surprisingly beautiful.

Look carefully at the words underneath the glass block.

The lettering appears to be raised upward, even though the paper is perfectly flat.

What Is Happening?

The thickness of the glass block is called the real depth.

However, when light travels from the lettering through the glass and into the air, refraction occurs.

As a result, your eyes trace the refracted rays backwards and perceive the image to be closer to the surface than it actually is.

This perceived distance is known as the apparent depth.

In Physics:

Apparent Depth < Real Depth

This is why the words seem to "float upwards" inside the glass block.

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Did You Notice Something Else?

Look carefully near the top surface of the glass block.

Besides the raised image, there appears to be a faint duplicate reflection of the dark lettering.

Why?

Because whenever light reaches a glass-air boundary, not all of it is transmitted.

A small fraction is reflected from the surface.

So in this single photograph, two optical phenomena are happening simultaneously:

✅ Refraction (creating apparent depth)

✅ Partial Reflection (creating a faint reflected image)

The glass block is quietly demonstrating both effects at the same time.

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AHA Moment

AHA! The words never moved. The glass simply changed where your eyes think they are. And while refraction lifts the image upward, reflection quietly creates a second one. Not by sight, but by INSIGHT!