D ropping a magnet into a conductive pipe (made up of copper or brass or aluminum) is a very popular demonstration in many physics classrooms and laboratories. In this paper we present an inexpensive timer that can be used to measure the terminal velocity of the magnet falling through a conducting pipe. The timer assembly consists of Hall effect switches connected to a digital stopwatch. The timer assembly was then used to observe the variation in the terminal velocity of the falling magnet with respect to the thickness of the copper pipes.

Thermal equilibrium is a basic concept in thermodynamics. In India, this concept is generally introduced at the first year of undergraduate education in physics and chemistry. In our earlier studies (Pathare and Pradhan 2011 Proc. episteme-4 Int. Conf. to Review Research on Science Technology and Mathematics Education pp 169-72) we found that students in India have a rather unsatisfactory understanding of thermal equilibrium. We have designed and developed a module of five activities, which are presented in succession to the students. These activities address the students' alternative conceptions that underlie their lack of understanding of thermal equilibrium and aim at enhancing their understanding of the concept.

An experiment with a mechanical black box containing unknown masses is presented. The experiment involves the determination of these masses and their locations by performing some nondestructive tests. The setups are inexpensive and easy to fabricate. They are very useful to gain an understanding of some well-known principles of mechanics.

The first law of thermodynamics involves several types of energies and many studies have shown that students lack awareness of them. They have difficulties in applying the law to different thermodynamic processes. These observations were confirmed in our pilot studies, carried out with students from undergraduate colleges across the whole of India. We, then, decided to develop an activity-based module to address students' conceptual difficulties in this area. In particular, we took up the cases of both adiabatic and isothermal compression of an ideal gas. We tested, through a two-group pre and post test design, the effectiveness of the module.

Recently devices such as the optical mouse of a computer, webcams, Wii remote, and digital cameras have been used to record and analyze different physical phenomena quantitatively. Devices like tablets and smartphones are also becoming popular. Different scientific applications available at Google Play (Android devices) or the App Store (iOS devices) make them versatile. One can find many websites that provide information regarding various scientific applications compatible with these systems. A variety of smartphones/tablets are available with different types of sensors embedded. Some of them have sensors that are capable of measuring intensity of light, sound, and magnetic field. The camera of these devices has been used to study projectile motion, and the same device, along with a sensor, has been used to study the physical pendulum. Accelerometers have been used to study free and damped harmonic oscillations and to measure acceleration due to gravity. Using accelerometers and gyroscopes, angular velocity and centripetal acceleration have been measured. The coefficient of restitution for a ball bouncing on the floor has been measured using the application Oscilloscope on the iPhone. In this article, we present the use of an Android device as a low-cost alternative for a signal generator. We use the Signal Generator application installed on the Android device along with an amplifier circuit.