An Affordable CCD Camera System for Introductory Physics Laboratories

物理入门实验室是大多数大学生体验实验科学基本要素的第一次机会。重要的是，这是一次积极和有益的经历。尽管我们目前的大多数实验都很有趣，可以教授重要的概念，但学生们经常陷入长时间的数据获取和处理过程中，他们正确地认为这些活动是“过时的”和“无聊的”。这个项目(物理系为改善入门实验室的教学和设备而进行的三年努力的一部分)试图将CCD摄像机和基于486的PC计算机引入实验室，从秋季学期的四个实验开始。(1)抛射运动。学生们得到了一张跳跃的超级球的闪光灯图像，显示了轨迹是抛物线，x和y运动分别是恒速和恒加速度。CCD摄像头和PC使数据还原(否则很费力)变得又快又有趣。(2)二维碰撞。冰球在空气桌上相撞，频闪图片被分析以研究线动量守恒。目前，学生们需要花费1到2个小时拍摄一张照片(宝丽来照片)并分析数据。一个CCD/PC系统在几秒钟内就能得到一张图片，并为学生提供许多可选的研究--弹性与非弹性、能量守恒、质心运动、变质量。(3)动态运动(一种新的实验)。摇晃墙壁，空气桌上的冰球形成了一种二维的“气体”。学生可以测量平均自由程或速度分布。(4)一项可选的实验测量了木星卫星的运动。这项提议的目标是开始将入门实验室从循序渐进的程序中转移到一个实验室，在那里，学生可以使用现代传感器和计算机，有选择地探索概念和尝试自己的想法。由于高性能的CCD摄像系统和基于486的个人计算机的低成本，该项目是可行的。

The introductory physics laboratory is the first opportunity for most college students to experience the basic elements of experimental science. It is important that the experience be a positive and rewarding one. Although most of our current experiments are interesting, and can teach important concepts, students frequently get bogged down in lengthy sessions of data taking and manipulation, activities which they correctly regard as "archaic" and "boring." This project (part of a 3-year effort by the Physics department to improve the teaching and equipment in introductory laboratories) seeks to introduce CCD cameras and 486-based PC computers into the lab, starting with four experiments from the fall semester. (1) Projectile Motion. Students get a strobed image of a bouncing superball, showing that the trajectory is a parabola and that the x and y motions are constant speed and constant acceleration, respectively. The CCD camera and PC make the (otherwise laborious) data reduction fast and fun. (2) Two Dimensional Collisions. Pucks collide on an air table and strobed pictures are analyzed to investigate conservation of linear momentum. Currently, students spend 1 to 2 hours getting a picture (Polaroid) and analyzing the data. A CCD/PC system gets a picture in seconds and offers a number of optional studies to the student -- elastic vs. inelastic, energy conservation, center of mass motion, varying mass. (3) Kinetic Motion (a new experiment). A 2-dimensional "gas" of pucks on an air table is excited by shaking walls. Students can measure the mean free path or speed distribution. (4) An optional experiment measures the motions of Jupiter's moons. The goal of this proposal is to begin to move the introductory lab away from step-by-step procedures which lead to an encircled number, toward a lab where students, using modern sensors and computers, can have options to explore concepts and try their own ideas. The project is made feasible by the low costs of highly capable CCD camera systems and 486-based personal computers.