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Physics and Astronomy Introductory Physics Labs

Lab Exam Information

Contents

What to bring

Lab manual
(We don’t normally have extra copies to supply during the exam.)
Your graded lab reports
Calculator
Pencil with eraser
Green engineering paper.

Ground rules

The exam will cover experimental techniques, methods of data analysis, and concepts covered during the semester in the lab. All of your graded lab reports for the semester and the lab manual are open for reference during the exam. Textbooks may not be used. Cameras and cell phones must be securely put away out of sight. Students will work on the exam alone—there will be no lab groups. Rulers will be available. You may be expected to set up Data Studio to collect data with sensors used during the semester. Microsoft Excel will not be available during the exam. All graphs must be drawn by hand. You have the entire 2-hour and 50-minute lab period to complete the exam, if necessary.

You will be expected to attend the lab section for which you are registered. Only with a valid reason and prior permission from the lab director can you take the lab exam with another section. Students needing special accommodations due to documented disabilities should contact the lab director at physlabs@wsu.edu. Special accommodations often require rescheduling that must be arranged in advance.

Grading

The lab exam makes up 20% of your lab grade. The lab director provides each teaching assistant the key to the exams with a breakdown of how much partial credit should be awarded for partial solutions. Each teaching assistant will grade the exams for their lab sections. The exam scores for each teaching assistant will be normalized to a mean of 85% and standard deviation of 7.5 %. Since the lab is 20-25% of your overall course grade (see your lecture syllabus), this is 4-5% of your grade for the whole course.

The graded exams will not be returned, but you are welcome to look at your exam by contacting your teaching assistant sometime after Wednesday of final exam week. Final lab grade sheets showing all report scores and the lab exam scores should be posted by lab section on the bulletin board on the third floor of Webster Hall by late on the Wednesday of finals week.

Exam Format

The lab exam consists of five equally weighted mini-experiments or exercises. Some of the equations and measurements you will need can found in the lab manual or in your graded lab reports. Explaining your method of solution is crucial! Some problems may require uncertainty analysis. Each task is clearly stated (hopefully), but don’t hesitate to ask your teaching assistant for assistance or clarification. At worst they can refuse to answer if they think you should already know.

For the mini-experiments, some data must be taken with provided equipment. During the first half of the lab period your teaching assistant will rotate you through the experiment stations with 7-10 minutes per station to get the required data. If you are unable to get the data you need during the first rotation, during the last half of the lab period you can return on a space available basis coordinated by your teaching assistant.

Sample Exercises using Data Supplied with the Exam

For Labs that Include Motion Analysis

Using graphical analysis find the mathematical relationship satisfied by the following data

Distance (m) on y-axis Time (s) on x-axis
4.23 1.10
5.86 1.73
10.7 3.64
8.75 2.87
17.2 6.19
14.3 5.08
12.1 4.21

For the object undergoing this motion, find its position, speed, and acceleration when the time equals 10.3 s.

For Labs that Include Imaging with Thin Lenses

A light source is located at the 0.00 cm point on an optical bench. A converging lens with a focal length magnitude of 8.00 cm is located at the 20.0 cm mark on the optical bench. Next a diverging lens with a focal length magnitude of 10.00 cm is located at the 28.0 cm mark on the optical bench.

(a) Where on the optical bench should a viewing screen be placed in order to see the real image formed by this lens combination?
(b) Assuming that the light source, or object that is being imaged, has a height of 2.0 cm, what is the height of its image as viewed on the screen?

Draw a ray diagram to scale for this lens configuration. Show all three principal rays for each lens.

Sample Exercises using Data Collected by the Student During the Exam

For Labs that Measure Velocity with Photogates

Using the computer and two photogates determine the value of the acceleration of the cart as it rolls down the incline. Do not adjust the slope of the incline or move the photogates horizontally or vertically! Take sufficient data so you can calculate a mean value for the acceleration and its standard deviation. When you have finished with Data Studio, please “quit” the program in preparation for the next person.

For Labs that Employ the Current Balance

Using the power supply, the circuit sf40, the electronic balance, and the appropriate measurements calculate the value of the magnetic field produced by the two disk magnets in the “gap” between them. From your measurements also determine which magnet (A or B) is acting as the N pole for producing this magnetic field. Be sure to record the number (#1 – #6) shown on the magnet pair that you used!