Chapter 10.1, Problem 2bT

Suppose that the bulb were replaced by a long filament bulb as shown.

Predict how the vertical length of the lit area would change if the diameter of the hole were halved. (In particular, would it become half as tall?) Explain in words and with a sketch.

Check your prediction. If your prediction was incorrect, resolve the inconsistency.

Predict the approximate height and shape of the lit region on the screen in the limit as the hole becomes very small, e.g., the size of a pinhole. (Hint: In this limit, would the lit region be taller than, shorter than, or the same height as the filament?)