Inverse Square Law Lab
Name _____________________________________________Date ________________ Period ___________
Purpose: To determine the relationship between force and distance according to the "Inverse Square Law" which
says that the force of attraction or repulsion between two objects is inversely related to the square of the distance
between them.
Hypothesis: If the distance between two magnets is ___________________then force of repulsion between them
will _____________________.
Materials: make a list of materials used in this lab
Ring Stand with attached magnet
Magnet "A" (repels magnet "B")
Magnet "B" (repels magnet "A")
Triple Beam Balance
Procedure:
1.) With the triple beam balance set away from the magnet on the ring stand measure the mass of the magnet. It should be
about 52 grams. Record this in your data table. This number will be subtracted from the measurements you will make next.
2.) Set up the apparatus according to the diagram above by moving the triple beam balance with magnet " B" under the ring
stand with magnet "A". Set the height of the ring stand so the distance between the magnets is 30 centimeters. Be sure the
magnets are aligned perfectly. Look at the setup from the top and the sides to adjust the alignment.
3.) Adjust the masses on the scale so that the reading is correct. Record this mass reading in your data table.
4.) Set the distance between the magnets at 25 centimeters. Adjust the scale and record the reading in your data table.
5.) Repeat the measurements by setting the magnets 20, 15, 10, 7, 5, 4, 3, 2 and 1 centimeter apart. Record each measurement
in the data table below.
DATA TABLE:
Column A
Distance Between
Magnets A & B
30 cm
25 cm
20 cm
15 cm
10 cm
7 cm
5 cm
3 cm
2 cm
1 cm
Column B
Mass of Magnet on
Balance
Column C
Mass Recorded
from Balance
Column D
Column C minus B
Column E
Estimated Force of
Repulsion
Divide Column D by 100
Newtons
Newtons
Newtons
Newtons
Newtons
Newtons
Newtons
Newtons
Newtons
Newtons
Graphs of Data: Set up a graph of Force verses Distance on the graph on the reverse side of this paper and draw the
curved line that represents the force of repulsion between the magnets. The "Y" axis represents the Force and should
extend from zero to 6 Newtons and the "X" axis represents the Distance and should extend from zero to 30
centimeters.
Analysis: Answer the following questions
1.) This lab is attempting to show the relationship described between forces of attraction and repulsion. What
law determines this relationship? __________________________________________________________
2.) Describe the relationship of attraction and repulsion between magnets according to your graph. Hint: As
the distance is decreased what happens to the force? As the distance increases what happens to the
force?_____________________________________________________________________________________
__________________________________________________________________________________________
3.) If the lab was done with the magnets attracting each other what would the graph look like? Describe it in
your own words. _______________________________________________________________________
4.) What would happen if four magnets were used? (two on the top and two on the bottom)
__________________________________________________________________________________________
5.) Imagine the magnets represent two protons in the nucleus of an atom. What happens to the force of repulsion
between the protons if they are very close together? ________________________________________
6.) Imagine the magnets represent a proton and an electron. What happens to the force of attraction if the electron is
far from the nucleus of the atom? ______________________________________________________