IB Magnet Design Lab

Pick a quantitative (numbers)  independent and dependent variable.  You can do B Field as a good dependent variable, or Force, and there are many many independent variables - distance from, current in an electromagnet, angle, length along an iron core

• • List your variables, and include a diagram of your setup

  • Gather 10 data points and their uncertainty

  • Make a data table with units and uncertainty

  • Make a graph with uncertainty (You can use an average uncertainty if you don't want to do individual error bars)  Your graph needs a plot frame and gridlines.

    • If your graph is linear do max min slopes by hand with a straight edge and a ruler.  Show your calcs

    • If your graph is curved, do a log log graph

  • Give me a function for your data

You will need the following in your final report

• Your variables (independent, dependent)

• A diagram (Hand drawn is fine.  I should be able to tell at a glance what you did)

• A data table with units and uncertainty

• An x-y scatter graph

• Either min max slopes or a log log graph of the same data

• Your function that describes your data.

Every man woman and child needs to pick their own variables and design their own data acquisition.

Old Stuff

and Either (Choose one)

• A full Design (See below) OR

• A full Conclusion and Evaluation (See Below)

Conclusion and Evaluation:

• 1. Summarize the results.  If there is a formula that applies, talk about whether that formula predicts your data.  Talk about trends - is it linear?

  2. Cite about three (at least) sources of error

  3. Explain how you would eliminate the three sources of error you mentioned

OR

Design:

Aspect 1: Stating the problem and listing the variables 

• State the problem concisely, and 

• list the independent, dependent and controlled variables. 

 Independent variables are the ones you manipulate, dependent are the variables you measure, and controls are the things that stay constant. 

Aspect 2: Method for control of variables 

• How you will manipulate the independent variable, 

• measure the dependent, and 

• make sure that the controlled variables don’t change. 

• Draw a diagram, include measurements of anything that matters, 

tell what equipment and materials you used, and give a step by step description of what you did. 

Aspect 3: Method for collecting sufficient data 

• You need to do a sufficient number of variations (5?) of the independent variables, 

• do an adequate number of trials (3?) of each variation, and the variations should be if possible well distributed throughout the possible range of variations. 

• You need to talk about what trials and variations you did.  State them explicitly.

 (Variations are like 5o, 10o, 15o, 20o, 25o, etc, and trials are repetitions of the same thing) 

Example: 

            Suppose I am doing an experiment to see how the parallel force depends on the angle of an incline.

Aspect 1: (After a bit of introductory information)

            The purpose of this investigation, then, is to determine the relationship between the force necessary to keep a wheeled cart from rolling down an incline, and the degree of that incline.  The independent variable is the degree of incline, the angle it makes with the horizontal, the dependent variable is the force needed parallel to the plane to hold the cart stationary on the plane, and the controlled variables include, but are not limited to the mass of the cart, the position on the plane, the type of surface used, and the angle of the force scale used to measure the force.

Aspect 2

            Our setup consists of a 2.0 m long inclined plane that we propped up using a pile of books.  (Insert a labeled diagram here)  We kept the mass of the cart constant at 1.85 kg, and always positioned the cart in the middle of the plane.  The angle we measured using a protractor placed on the table surface, and we measured the force using a 20 N force scale for all trials.  We took special care to keep the force scale parallel to the surface when we measured the force.  To gather a data point, our procedure was this:  First, we propped up the plane to the angle we desired, and measured this carefully keeping the protractor level with the table surface.  Second, we tipped the force scale parallel to the plane, and made sure the scale read zero.  If not, we adjusted the zero.  Then we carefully attached the cart in the middle of the plane, and very slowly let it exert a force on the scale.  We then read the force on the scale.

Aspect 3

            We chose to try the following angles: 10, 20, 30, 40, 50, 60, and 70.  We could not get the plane to remain stationary for 80 degrees.  For each variation, we did four trials of each angle to make sure that the measurements were repeatable.