In this experiment we have first determined the focal length of an equiconvex lens. We have observed that a real image can be formed by the lens on the same side of the source if the source is sufficiently strong. This is due to the reflection from the concave surface of the lens. We have measured these image distances for different object…

In introductory texts, some "special" rays are selected to draw the image produced by lenses and mirrors. After teaching special rays, students usually ask how to draw an arbitrary ray. One method for drawing an arbitrary ray is the "tilted principal axis." As an example, the tracing of an arbitrary ray in diverging lens is…

The refractive index (RI) is probably the single most important parameter in optical systems. Chromatic dispersion, on the other hand, indicates how the RI depends on the wavelength and is central in, e.g., optical communication systems. Chromatic dispersion also plays an important role when teaching optics due to the captivating natural…

The wave nature of light has been widely demonstrated in a double-slit experiment, which has played a special role in physics teaching. When monochromatic light passes through the double-slit sheet, the diffraction and interference fringes can be observed in the far-field regime. The interference of light causes the beams passing through the two…

Diffraction refers to a kind of optical phenomena which occurs when light approaches an element (object or aperture) whose features are in the range of the illuminating wavelength (small apertures, sharp edges). It can be explained by means of the undulatory nature of light or also geometrically by using simple ray optics. Diffraction phenomena…

On April 14, 1912, the British passenger liner R.M.S. "Titanic" struck an iceberg. The ship sank in a fraction of the time designers had estimated following a worst case scenario. The purpose of this article is to examine the atmospheric refractive phenomena that might have played a significant role in obscuring the iceberg from…

The falling temperature of the photosphere with height is responsible for the effect known as limb darkening. The Sun is not equally bright all over the disc. When we observe the Sun towards the limbs, it appears to get darker. Light from the photosphere travels through an absorptive medium. Therefore, one can see only so far into the photosphere.…

Although it originates from the ancient Greeks, optics still arouses a lot of scientific interest, mainly due to the technological innovation associated with it. One of its most interesting applications is related to optical metrology and the characterization of materials through optical techniques. While some of these processes can be explained…

Demonstration interviews with 27 high school students (18-19 years old) were conducted in Zagreb, Croatia, using several standard experiments on interference and diffraction of light. Students were asked for their predictions, observations, and explanations of the experiments. In this process, many student difficulties were identified, both…

The field of geometrical optics features a broad knowledge base concerning conceptual learning difficulties and student conceptions. However, in contrast to other areas of physics, no widely used standard test instrument exists to assess middle school students' conceptual knowledge of geometrical optics. This is even more true for other areas of…

The laser pointer has been widely used to demonstrate some simple optics phenomena, like reflection, refraction, total reflection, and diffraction. However, the rays of laser light cannot be seen in the air because the scattered light is too weak. Many physics teachers use milk or smoke to visualize rays of laser light in physics labs, but it is…

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…

In this article, simple models of optical computing circuits (1 x 4 demultiplexer (DEMUX), 4 x 1 multiplexer (MUX), Boolean logic, and half-adder (HA)) are shown with mechanically controlled plane mirrors. Photographs of the proposed computational circuits are also shown. It is very useful for the school student to understand optical logic and…

Visual representation in school textbooks plays an important role for physics teaching and learning. The integration of graphics with text has drawn attention of physics educators in recent years due to the close relationship between graphics and relevant text. The purpose of this study is to examine visual representation of optical content in…

Students are often introduced to optics in their middle school years. The initial topics that are introduced through their lessons are laws of reflection and refraction of light. In the law of reflection, students do not often question why the angle of incidence is equal to the angle of reflection and why a light ray should follow this specific…