Pinhole Camera

• How a pinhole camera forms an inverted image using rectilinear light rays.
• The parts of a simple pinhole camera — box, pinhole, screen.
• Why the image is upside down and how hole size affects sharpness and brightness.
• To connect pinhole imaging to eclipses and early photography (historical context).

Level 1 — How a pinhole camera works

Verbal: Light from the top of an object passes through a tiny hole and hits the bottom of the screen inside a dark box — image is inverted.

Visual: Top of tree → ray through pinhole → bottom of screen; bottom of tree → top of screen.

Parts:

Properties: Image is real (forms on screen), inverted, and usually dimmer than object.

Level 2 — Hole size, distance, and eclipses

Smaller hole: Sharper but dimmer image.

Larger hole: Brighter but blurred image (multiple crossing rays).

Moving screen: Farther screen → larger but fainter image.

Eclipse link: Tiny gap between fingers can project crescent Sun image — same rectilinear idea (never look directly at Sun).

History: Precursor to modern cameras; lens replaced pinhole for brighter images (Class 7+).

Build and use a pinhole camera (NCERT-style activity).

Step 1 — Take a cardboard box; make a small pinhole on one face.
Step 2 — Replace opposite face with tracing paper (screen).
Step 3 — Point pinhole at a bright object (lamp or tree in sunlight).
Step 4 — Observe inverted image on screen; cover box except pinhole
Step 5 — Enlarge hole slightly — note image gets brighter but less sharp

• Why is the pinhole camera image inverted?
• What happens if the pinhole is made too large?
• Name the three main parts of a pinhole camera.
• How is a pinhole camera related to the idea that light travels in straight lines?

Open the Practice tab for graded questions on Pinhole Camera.