Document Type

Article

Publication Date

2024

DOI

10.1119/5.0178541

Publication Title

Physics Teacher

Volume

62

Issue

6

Pages

A543

Abstract

The article titled "Shadow hands: Solutions for Fermi Questions, September 2024" discusses the enigmatic statement made by authors Dave Lynch and Bill Livingston in their book "Color and Light in Nature." The statement explains that the fuzzy outer edge of a shadow, known as the penumbra, is always a constant fraction of about 1/112 of its width divided by its distance from the object casting the shadow. The article provides a solution to Question 1, which asks for an explanation of this statement using elementary geometry. It also offers a solution to Question 2, which asks why the shadow of a tall object becomes less sharply defined as you gaze away from the shadow base. The article includes diagrams and mathematical equations to support the explanations.

Rights

© 2024 Author.

Included in accordance with publisher policy.

Original Publication Citation

Adam, J. (2024). Shadow hands: Solutions for Fermi questions, September 2024. Physics Teacher, 62(6), A543. https://doi.org/10.1119/5.0178541

ORCID

0000-0001-5537-2889 (Adam)

Available for download on Monday, September 01, 2025

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