The camera obscura is a well-known optical device in the form of a closed box with a hole in one of its walls through which light rays pass, forming an inverted image of the external objects on the opposite wall, as can be seen in Fig. 1(a). Despite the simplicity of its basic design, they have been widely used by scientists and artists. In…

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…

In this study, we propose a novel and direct method of determining the focal length of a converging or diverging lens using a smartphone. The standard optical sensor used in modern smartphone cameras is an active-pixel sensor called the complementary metal-oxide-semiconductor (CMOS). The CMOS is covered by an assembly of five to seven camera…

We demonstrated that an optimally designed pinhole camera can be used as an astronomical tool to observe the libration and apparent diameter change of the Moon at night. The libration and apparent diameter change of the Moon were observed using a handmade pinhole camera with a diameter of 0.65 mm and a focal length of 400 mm. It was found that the…

This paper proposes a simple method to design experiments for drawing the light paths at a lens to find its effective focal length and principal planes. In the designed experiments, long-exposure photography was used to record the light scattered using a moving sheet of paper, thus revealing the light path. According to the proposed experimental…

Nowadays more than two billion people own smartphones, without necessarily realizing they have a mobile physics lab that can be used to study acoustics, mechanics, astronomy, optics, fluids mechanics, or even serves as an oscilloscope. All smartphones have at least one camera, which is probably the most well-known and used sensor of this device.…

Astrophotography has been responsible for the discovery of planets, solar systems, stars, and several other celestial objects, which directly helps with expanding our knowledge about the universe and creating scientific models for nature. Practical techniques have been extensively described, including Covington, who has published an extensive…

I had been sitting in a coffee shop in Reykjavik, Iceland, cycling through my photographs of the aurora borealis from the night before in Njardvik, when a man at the next table struck up a conversation. Recognizing his familial ties to the location in my photographs, he began to share stories that his grandfather told him as a child regarding the…

Many of us teach that insects can see "invisible" ultraviolet light, but what demonstrations do we perform to illustrate this? Often UV can be used to cause fluorescence or phosphorescence, which can make its existence more visible. But, is it possible to create photographs or videos that convincingly illustrate the vision of insects? In…

From ancient times, the different features of planets and moons have created a huge interest. Aristarchus was one of the first to study the relative relations among Earth, Moon, and Sun. This interest has remained until today, and therefore it is always relevant to make this knowledge more appealing to the younger generations. Nowadays, smartphone…

This paper mainly proposes a simple method to record scattered light rays via photography, presenting a clearer and brighter representation of the optical path. This technique is applied to the double-slit interference experiment and single-slit diffraction experiment typically conducted in general physics courses, and shows the intuitive results…

Light rays refract when passing through pockets of transparent fluids with different indices of refraction such as ordinary air pockets of varying temperature. This phenomenon makes night stars twinkle, distorts views above hot asphalt roads and hot barbeque grills, and provides an opportunity for visualizing the normally invisible movement of…

This paper describes a conservation of momentum experiment using just smartphones and two beach balls, thus making the experimental study of this movement available to any classroom. For a more thorough analysis of the data, a computer can also be used. Experiments making use of smartphone sensors have been described before, contributing to an…

The planets in our solar system are remarkable and captivating objects for beginning astronomers to study. While merely observing the planets is fairly easy, it can be difficult to capture the high-quality images beginners hope for. The methods used for deep-sky astrophotography are optimized for dim, fairly large objects using large apertures and…

Everyone who has visited an art museum and stood before a masterful painting has admired the artist's clever use of accurate perspective to bring a third dimension to the flat canvas. The mathematical theory of perspective is almost 600 years old, having been pioneered by Leon Battista Alberti (1404-1472) in his treatise "De Pictura"…