Teacher Notes



Teacher Notes
Publication No. 12551
Measuring Magnetic ForceStudent Laboratory KitMaterials Included In Kit
Neodymium magnets, 16
Paper clips, 1 box Plastic containers, large, 8 Plastic containers, small, 8 PVC tubes, 8 String, 1 ball Additional Materials Required
Balance, 1g precision
Graph paper (loglog graph paper, optional) Ruler, metric Scissors Spring scale, 500 g/5 N Support stand Support stand clamp Tape, transparent Safety PrecautionsThe materials in this lab are considered nonhazardous. Use care when handling the strong magnets. The magnets can quickly snap together, resulting in pinched fingers or cracked magnets. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. DisposalThe materials should be saved and stored for future use. Lab Hints
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Correlation to Next Generation Science Standards (NGSS)^{†}Science & Engineering PracticesPlanning and carrying out investigationsDisciplinary Core IdeasMSPS2.B: Types of InteractionsHSPS2.B: Types of Interactions Crosscutting ConceptsCause and effectPerformance ExpectationsMSPS25. Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact Sample DataMass of small container and magnet: ___10 g___ {12551_Data_Table_1}
Answers to Questions
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Student Pages


Student PagesMeasuring Magnetic ForceIntroductionThe force due to gravity between two massive objects and the force due to electrostatic charge between two electrical charges behave similarly. In both cases, when the distance between the two objects changes, the change in magnitude of the force is inversely proportional to the distance between them (F ∝ 1/d^{2}). Discover the relationship between the force due to magnetism exerted by two repelling magnets and their separation distance. Concepts
BackgroundForces hold the universe together. Everything from huge galaxies to tiny atoms are held together by the one or more of the four “fundamental” forces—strong and weak nuclear forces, gravitational force, and electromagnetic force. While it is not possible to “see” a force, the effect that forces have on objects can be observed and studied. In this experiment, the effect of the magnetic force will be apparent as one container “floats” inside another container in seeming defiance of the force due to gravity. The force due to gravity and the force between two magnets each depend on two properties—an intrinsic property of the material (i.e., an object’s mass for gravitational force and the magnetic moment of a magnet), and the distance between the objects. {12551_Background_Equation_1}
F = force In this experiment, the mathematical relationship between the magnitude of the magnetic force and the separation distance between two magnets will be determined using dipole magnets. The general expression can be written: {12551_Background_Equation_2}
F = force {12551_Background_Equation_3}
{12551_Background_Equation_4}
{12551_Background_Equation_5}
{12551_Background_Equation_6}
In logarithm form, an exponential equation (Equation 2) becomes a linear equation (y = mx + b). In the linear equation, log (d) represents “y,” log (F) represents “x,” –1/n represents “m,” and [log (A)]/n is a constant and represents “b.”
Experiment OverviewMeasure the separation distance between two dipole magnets subjected to a compressing force (mass). By plotting the log of the separation distance versus the log of the force (mass), the slope of the line can be calculated. Take the inverse of the magnitude of the slope to determine the exponent (n) to see the relationship between force and distance between two dipole magnets. Materials
Balance, 1g precision
Graph paper Neodymium magnets, 2 Paper clip Plastic container, large Plastic container, small PVC tube Ruler, metric Scissors Spring scale, 500 g/5 N String Support stand Support stand clamp Tape, transparent Safety PrecautionsThe materials in this lab are considered nonhazardous. Use care when handling the strong magnets. The magnets can quickly snap together, resulting in pinched fingers or cracked magnets. Wash hands thoroughly with soap and water before leaving the laboratory. Procedure
Student Worksheet PDF 