There are already several articles describing ways to teach physics using smartphone apps, but what are some experiments you can perform immediately without downloading any additional software? In the spirit of increasing the amount of hands-on activities each of us is doing, and to give us backup activities when you have a few extra minutes of class, I present these experiments that can be done without downloading an app or (in most cases) purchasing any new equipment. All that is required is the now ubiquitous smartphone. In my case it is an iPhone 6s, but these five tricks should work for essentially every smartphone.

1.
As illustrative examples, I present these nice articles about smartphones using apps:
Jochen
Kuhn
and
Patrik
Vogt
, “
Analyzing spring pendulum phenomena with a smartphone acceleration sensor
,”
Phys. Teach.
50
,
504
(
Nov.
2012
), and
Yasuo
Ogawara
,
Shovit
Bhari
, and
Steve
Mahrley
, “
Observation of the magnetic field using a smartphone
,”
Phys. Teach.
55
,
184
(
March
2017
).
2.
Usually this experiment is done with a mirror and a trustworthy partner who can verify that your eyes move, but I trust the camera more. The effect is called “saccadic masking,” or chronostasis; see https://en.wikipedia.org/wiki/Saccadic_masking.
3.
Mark
Davids
,
Rick
Forrest
, and
Don
Pata
, “
Teaching the fundamentals of cell phones and wireless communications
,”
Phys. Teach.
48
,
217
(
April
2010
).
4.
This demo came to me from Martin Simon of UCLA. I performed it here in our video “Do Cell Phones Cause Cancer,” https://www.youtube.com/watch?v=0FTDWAXL3KI.
5.
Udi
Tirosh
, “
Everything You Wanted to Know About Rolling Shutter
,”
Photography
, https://www.diyphotography.net/everything-you-wanted-to-know-about-rolling-shutter/. This website has many helpful animations and descriptions for understanding the rolling shutter effect.
6.
Dan
MacIsaac
, “
WebSights: Smartphones in a guitar redux
,”
Phys. Teach.
53
,
190
(
March
2015
).
7.
You can print a Snellen chart for free here and learn about how to use it! https://www.allaboutvision.com/eye-test/snellen-chart.pdf.
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