Pinhole camera
Light travels in straight lines, yet the image comes out upside down.
Light travels in straight lines in a uniform medium. Light from each point on the object passes through the pinhole and lands on a single point of the screen, flipped top to bottom and left to right, forming an inverted real image. The image size is set by the ratio of image distance to object distance and does not depend on the shape of the hole.
Image height vs. image distance
With object distance and object height fixed, image height is proportional to image distance.
Think about it
What happens to the image if you move the screen farther from the pinhole?
It gets larger and dimmer. The image height h′ = h·v/u grows with the image distance; the light passing through the pinhole stays the same but is spread over a larger area, so the image is dimmer.
Model assumptionsPinhole small enough · light travels in straight lines · brightness estimated as 1/v², taken as 1 at v = 15 cm
Data log
Set the parameters and click “Record data”. Record several rows with different parameters to plot their relationship and fit a straight line; pause and record at different times to study how a reading changes with time.