The pin-hole camera produces a less sharply defined image when the

Analysis

This question tests your understanding of the principles of light and image formation in a pin-hole camera. You are asked to identify the condition that causes the image to lose its sharpness (become blurred).

Concept Explanation

A pin-hole camera works on the principle of the rectilinear propagation of light (light travels in straight lines).

• How it works: Light rays from an object pass through a tiny hole to form an inverted image on a screen.
• The "Pin-hole" effect: For a sharp image, the hole must be very small (approaching a point source).
• The problem with a large hole: If the pin-hole is made larger, each point on the object sends a "beam" of light through the hole rather than a single ray. This beam covers a larger area on the screen, causing the light from adjacent points on the object to overlap. This overlapping results in a blurred or "less sharply defined" image.

Step-by-Step Solution

1. Evaluate Option A: A larger pin-hole allows more light rays from different parts of the object to pass through and overlap on the screen, creating a blurred image. This matches the definition of "less sharply defined."
2. Evaluate Option B: Illumination (brightness) affects the intensity of the image, not its sharpness.
3. Evaluate Option C: Moving the screen further away increases the magnification of the image, but it does not inherently make it "less sharp" in the context of the pin-hole size.
4. Evaluate Option D: Moving the object further away changes the size of the image, but does not affect the sharpness caused by the aperture size.

Conclusion

The sharpness of an image in a pin-hole camera is inversely proportional to the size of the hole. As the hole gets larger, the image becomes more blurred. Therefore, the correct condition is that the pin-hole is larger.

Exam Tip: Always remember the "Small Hole, Sharp Image" rule. If you are ever asked how to make the image sharper, the answer is always to make the pin-hole smaller. Conversely, making the hole larger makes the image brighter but blurrier.