摘要:

Optical crystals are one-, two-, and three-dimensional diffraction plates used to demonstrate Laue diffraction by using light rather than x rays or particles. The flexibility afforded by optical crystals makes them better suited for demonstration purposes than naturally occurring crystals. The sequence of optical crystals has been proven effective for demonstrating diffraction phenomena at the high school level and is applicable at all university levels in both classroom and laboratory situations.

ISSN:0002-9505    

DOI:10.1119/1.1987621

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

There is described the principle, construction, and operation of a simple apparatus to demonstrate the non-colinearity of the angular velocity vector and the angular momentum vector. Some details of the theory are given, as are complete details for the construction and operation of the apparatus. The apparatus is useful for individual or group demonstrations and helps students increase their understanding of angular velocity, angular momentum, and the inertial tensor.

ISSN:0002-9505    

DOI:10.1119/1.1987622

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

A water stream is “looping-the-loop” on the inside of a vertical, circular track made from an aluminum tubing cut along its length. The apparatus demonstrates the effect of centripetal (centrifugal) forces much more dramatically than when a ball is used. Although the track is only34-in. wide and only38-in. deep, the water is completely confined to it even at the uppermost portion of the loop. The water inside the loop can drive a small paddle wheel, and small boats can make the loop when dropped on the water stream at the bottom of the track. The apparatus has a built-in pump for pumping the water from the reservoir in the base of the apparatus to the starting point of the track.

ISSN:0002-9505    

DOI:10.1119/1.1987623

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

A simple device to demonstrate the principles of acceleration and phase stability in a cyclotron is described in which a steel ball is accelerated gravitationally along a spiral groove. The principle can be extended to demonstrate acceleration in a linear accelerator.

ISSN:0002-9505    

DOI:10.1119/1.1987624

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

An apparatus is described which permits general physics laboratory students to measure forces dynamically. The apparatus consists of four strain gauges, mounted two on each side of a flat spring, which form the arms of a Wheatstone bridge. The spring is cantilevered with the force to be analyzed applied at the free end. As the spring is flexed, resistance of the gauges change producing a voltage signal from the bridge which is observed with an oscilloscope. An experiment using the apparatus to measure centripetal force of a pendulum is also described.

ISSN:0002-9505    

DOI:10.1119/1.1987625

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

Magnetic levitation is seriously being considered as a method of supporting high-speed guided vehicles. In this article we review the present status of magnetically levitated trains with particular emphasis on the use of superconducting magnets. We present the basic theory for the lift and drag forces of a magnetically levitated vehicle riding over a conducting sheet guideway. To obtain experimental results we have designed and constructed a superconducting magnetically levitated merry-go-round on a laboratory scale. This simple apparatus permits observation of all the principal characteristics of a much larger magnetically levitated vehicle. The “train” consists of six fixed, alternately positively and negatively oriented, superconducting solenoids held in a 2-in diam liquid helium dewar and suspended above a rotating dish track. A simple pan balance measures the levitation force which in this experimental geometry is downward. The track is driven by a small dc motor through a thin-walled stainless steel shaft and pulley. The electrical power into the dc motor gives a measurement of the drag force. The sample disk tracks are threaded onto the end of the steel shaft, allowing the quick interchange of track samples to test different track configurations. Stanford students in the Advanced Applied Physics Laboratory designed and built the apparatus for this highly successful experiment of current interest.

ISSN:0002-9505    

DOI:10.1119/1.1987626

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

We report on the philosophy and operation of a self-instructional laboratory to support introductory physics courses, including those which are self-paced. The laboratory features demonstrations and experiments which, in most cases, yield quantitative data. The instruction is accomplished by means of displays of visual and printed material and, most importantly, by means of audio recordings with each experiment.

ISSN:0002-9505    

DOI:10.1119/1.1987627

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

A high Q acoustical resonant chamber which can be used to investigate a wide variety of wave phenomena is described. Several short experiments are discussed and typical results are given in graphical form.

ISSN:0002-9505    

DOI:10.1119/1.1987628

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

This project concerns itself with the diffraction of microwave radiation from the three dimensional planes of a macroscopic crystal model. A study of earlier activities indicates that microwave diffraction studies on ordered matrices have been done on model systems that do not represent crystals but only accurately spaced reflecting surfaces. In order to demonstrate diffraction techniques from macroscopic crystal structures, it was assumed that: (1) the reflecting surfaces of a working model could be embedded within a styrofoam ball model that represented the supposed shape of the atom or ion, and (2) microwave energy reflected from a surface is proportional to the surface area of that surface as is the x-ray energy reflected proportional to the atomic number of the atom or ion for small angles of incidence. The analysis of x-ray diffraction data concerns itself with Bragg angle measurements and the intensity of the Bragg reflections. Intensity results from macroscopic models have previously not been reported. In addition to the quantitative results obtained for the Bragg angles, qualitative results for intensity measurements could not be expected from a macroscopic model since: (1) The lack of collimators and filters for the microwave source permitted other than parallel monochromatic wavefronts; and (2) only a limited number of unit cells are possible if a reasonable sized model is to be preserved. The laboratory investigations, prepared to utilize the equipment developed in the classroom, serve also to introduce the computer as a teaching and problem-solving aid. The study indicates that crystal models can be built with structural alterations and doping that can be detected with microwave techniques. Additional laboratory investigations and the existing computer programs can be utilized to study the properties of imperfect crystals in the classroom.

ISSN:0002-9505    

DOI:10.1119/1.1987629

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP

摘要:

The charge-to-mass ratio of charged, freely-falling water drops is measured in two ways: from their deflection in a horizontal electric field and from the total charge delivered by a large number of drops to a Faraday cup. The apparatus needed is simple and inexpensive. The data analysis requires the combined use of several concepts generally encountered separately. Suitable choice of parameters allows the study of (1) one-dimensional uniform acceleration, (2) two-dimensional uniform acceleration, or (3) uniform horizontal but non-uniform vertical acceleration.

ISSN:0002-9505    

DOI:10.1119/1.1987630

出版商:American Association of Physics Teachers    

年代:1974

数据来源: AIP