An improvement of the experiment with a driven pendulum is proposed: during a run, the phase shift between the driving force and displacement is continuously displayed vs. frequency. The method of phase measurements is taken from the lock-in detection technique. Using the new PASCO data acquisition system, the measurements in a frequency range…

A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The "h/e" ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a…

Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…

Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the…

A common moving-coil loudspeaker is useful for learning harmonic motion. A simple optical method is used to observe free and forced oscillations of the diaphragm of a loudspeaker. With a lock-in amplifier and data-acquisition system, the frequency response of the loudspeaker and its electrical impedance are automatically recorded versus frequency.…

An experiment is proposed for learning the principles of radio. A simple radio receiver illustrates amplitude modulation and demodulation, the selectivity of a receiver and the features of a directional antenna. Both normal and computerized versions of the experiment are described. The computerized experiment employs the "ScienceWorkshop"…