A smartphone is a powerful learning aid in the hands of a large section of students around the world. The camera of the phone can be used for several learning purposes apart from its obvious purpose of photographing. If the focal length of the lens of the camera can be determined, several experiments in optics can be performed with it. In some recent works, the method for determination of the focal length has been discussed. When a real image of an object is formed by a lens of known focal length, one can determine either the distance or the transverse magnification of the object if the other is known. In this work, we have shown that we can determine both the transverse size and the distance of an object, by photographing it from two positions, separated by a distance along the line of sight of the camera. In a few other works, the smartphone camera has been used for conducting experiments in optics.

1.
Jun
Wang
and
Wenqing
Sun
, “
Measuring the focal length of a camera lens in a smart-phone with a ruler
,”
Phys. Teach.
57
,
54
(
2019
).
2.
Antoine
Girot
,
Nicolas-Alexandre
Goy
,
Alexandre
Vilquin
, and
Ulysse
Delabre
, “
Studying ray optics with a smartphone
,”
Phys. Teach.
58
,
133
135
(
2020
).
3.
Jack
Freeland
,
Venkata Rao
Krishnamurthi
, and
Yong
Wang
, “
Learning the lens equation using water and smartphone/tablets
,”
Phys. Teach.
58
,
360
361
(
2020
).
4.
Mickey D.
Kutzner
and
Samantha
Snelling
, “
Measuring magnification of virtual images using digital cameras
,”
Phys. Teach.
54
,
503
(
2016
).
5.
Timo
Hergemoller
and
Daniel
Laumann
, “
Smartphone magnification attachment: Microscope or magnifying glass
,”
Phys. Teach.
55
,
361
364
(
2017
).
6.
A.
Pons
 et al, “
Learning optics using a smartphone
,” in
ETOP 2013 Proceedings
(
Optical Society of America
,
2013
), paper EWP13.
7.
Shangwen
Chen
 et al, “
Single-image distance measurement by a smart mobile device
,”
IEEE Trans. Cybern.
47
,
4451
4462
(
2017
).
8.
Suraphol
Laotrakunchai
 et al, “
Measurement of size and distance of objects using mobile devices
,”
International Conference on Signal-Image Technology and Internet-Based Systems, IEEE Conference
(
Kyoto, Japan
,
2013
).
9.
Jesus J.
Barreiro
 et al, “
Diffraction by electronic components of everyday use
,”
Am. J. Phys.
82
,
257
261
(
2014
).
13.
Sanjoy Kumar
Pal
,
Soumen
Sarkar
, and
Surajit
Chakrabarti
, “
Determination of the refractive index of water and glass using smartphone cameras by estimating the apparent depth of an object
,” arXiv:2111.06735v1 [physics.ed-ph] (submitted Nov. 11, 2021).
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.