The letter appear to be raised when viewed through a glass slab placed over the document. What is the phenomenon called?

Options

A. Reflection
B. Refraction
C. First reflection, then refraction
D. First refraction then reflection

Explanation

**Step-by-Step Solution:**

1. **Understanding the Setup**: We have a document with letters written on it, and a glass slab is placed over this document. When we look at the letters through the glass slab, they appear to be raised.

2. **Identifying the Phenomenon**: The phenomenon that causes the letters to appear raised is due to the bending of light as it passes through different mediums. This bending of light is known as refraction.

3. **Explaining Refraction**: When light travels from air (a less dense medium) into glass (a denser medium), it slows down and bends towards the normal line (an imaginary line perpendicular to the surface at the point of incidence). This bending causes the light rays to change direction.

4. **Apparent Shift**: The apparent position of the letters is shifted due to this bending of light. Instead of seeing the letters at their actual position, we see them at a higher position. This shift in the perceived position of the object is called the "apparent shift."

5. **Conclusion**: Since the letters appear to be raised due to the bending of light, the phenomenon we are observing is called "refraction."

**Final Answer**: The phenomenon is called "refraction."

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