As we move away from the edge into the geometrical shadow of a straight edge, the intensity of illumination

Options

A. decreases
B. increases
C. remains same
D. none of the above

Answer

To solve the question regarding the intensity of illumination as we move away from the edge into the geometrical shadow of a straight edge, we can follow these steps:

### Step 1: Understand the Concept of Diffraction
Diffraction is the bending of waves around obstacles and the spreading of waves when they pass through small openings. When light encounters an edge, it does not just stop; it bends around the edge, leading to a pattern of light and dark regions.

**Hint:** Recall that diffraction occurs when waves encounter an obstacle or aperture, causing them to spread out.

### Step 2: Identify the Geometrical Shadow
The geometrical shadow is the area behind the edge where light cannot travel in a straight line. However, due to diffraction, light can still reach this shadowed area, albeit with reduced intensity.

**Hint:** Consider how light behaves when it encounters an obstacle and how it can still reach areas that are geometrically shadowed.

### Step 3: Analyze the Intensity of Illumination
As we move away from the edge into the geometrical shadow, the intensity of illumination is affected by the diffraction pattern created by the edge. The central maximum (brightest part) is closest to the edge, and as we move further away, the intensity decreases.

**Hint:** Think about how the intensity of light changes in a diffraction pattern, particularly in relation to the central maximum.

### Step 4: Conclude on the Intensity Trend
From the understanding of diffraction, we conclude that as we move further away from the edge into the geometrical shadow, the intensity of illumination decreases. This is because the light waves spreading out from the edge become less concentrated as we move away from the source of the diffraction.

**Hint:** Remember that in diffraction patterns, the intensity typically decreases as you move away from the central bright region.

### Final Answer
As we move away from the edge into the geometrical shadow of a straight edge, the intensity of illumination decreases.