The pendulum was an important scientific instrument in the 17th century. It became a typical textbook problem in the 18th century. After the introduction of vectors in physics in the 1890s, the pendulum problem started to be progressively solved in the manner we know nowadays from introductory mechanics courses. Starting from "F = ma"…

Introductory lab courses have been a staple of the physics curriculum for over 100 years. Yet these courses are now poised for change as recent research shows that they do not meet a frequent goal of enhancing student understanding of lecture content. In thinking about how to move forward, a look back at experiment courses in history seems wise.…

Oblique angle collisions of two penny coins on a smooth, horizontal surface were filmed with a video camera to investigate the physics of the collision process. If one of the coins is initially at rest, then the two coins emerge approximately at right angles, as commonly observed in billiard ball collisions and in puck collisions on an air table.…

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…

In general, undergraduate experimental physics laboratories do not usually have experiments designed to address rolling friction and to measure the value of the rolling friction coefficient. This work explores an experiment, which has the potential to arouse students' curiosity about rolling friction by addressing a counterintuitive aspect of the…

The Crookes radiometer (also known as a light mill) is a fascinating sunlight-powered device, in which a set of vanes is placed inside a glass bulb within which a partial vacuum has been pulled. The vanes then rotate when sunlight shines on the bulb. The reason for the turning of the vanes was subject to intense debate and many students still have…

Einstein's relation between mass and energy is perhaps the most famous equation of Physics. Despite its simplicity, the meaning of E[subscript 0] = mc[superscript 2] is not easy to grasp. Furthermore, its traditional derivations rely either on the integral of "momentum," on properties of electromagnetic radiation, or even on the…

When the thermal expansion of water is discussed in school or university lessons, functional relationships are often inferred without considering measurement uncertainties. Moreover, in some learning materials, the goal of experimentation and the experimental setup do not match. This creates the wrong picture of scientific practice. In this…

Scientific laboratories are among the most challenging course components to integrate into online instruction. Available technology restricts the design and nature of experiments, and it can be hard to replicate the collaborative lab environment where frequent and immediate instructor feedback is the norm. Here we report on technological and…

It is a well known fact that the Earth carries a net negative charge that produces a downward electrostatic field. The present experiment shows how this field can be measured with a Field Mill which has been constructed from components readily available in the Laboratory. In fine weather conditions a value of 120 (±10) V m[superscript -1] was…

In the light of own measurements on a Faraday generator, the well-known theories concerning Unipolar Induction and the Faraday paradox seem to be problematic. On the other hand, all results obtained, and all other processes described as a paradox in connection with the Faraday generator can be explained without contradiction based on the theory of…

Two balls on an incline can remain at rest if friction between the balls prevents them rolling down the incline. Results with various balls are presented to show how ball mass, diameter and friction affects the outcome. A stack of four identical balls is also examined.

In this paper we consider the well-known experiment with the 'heavy' newspaper that breaks a stick that it is laid on. Using several appropriate control experiments we show that the currently invoked explanation using atmospheric pressure cannot be correct. We perform a theoretical analysis and propose a new explanation based on the rotational…

A previous journal article established that a hanging Slinky's restoring force is due only to the coils between the support and the Slinky's center of mass (hereafter COM). Correspondingly, it is expected the Slinky's elastic potential energy (hereafter EPE) is associated with only those coils; however, there is no confirming experimental…

We have demonstrated both interference and diffraction of a pseudo-double slit using two glass plates with a width and a length of about 5 cm and a thickness of about 5 mm. The plates are attached at the upper and lower ends with Scotch tape of about 0.1 to 0.3 mm between the plates. By adjusting the angle between the two plates, we are able to…