A paper clip lying on a smooth piece of paper will be pulled across the paper to stick to a nearby disk magnet-if they are close enough together. How close is close enough?
Do an experiment to answer this question. Here are some
ideas:
The distance undoubtedly depends on the orientation of
paper clip and of the magnet. So first do a short preliminary
study to see what combination works best.
There are other variables that we need to be aware of: for example,
the roughness of the paper, and whether there are nearby magnetic
objects (such as a steel desk!). These won't change during your experiment,
but other people might make other choices and get different results.
It's good science practice to be aware of these "uncontrolled" variables.
One way to define the range of the force is to place a paper clip at
the zero line at the left end of a ruler, and slowly move the magnet down the scale
from the right until the paper clip moves.
You should repeat each measurement several times. The results will not abe
all the same, so calculate the median.
Determine the range of the magnetic force for one through four magnets, and
make a graph of the results.
A quantitative measurement of this sort could be the starting point for many
investigations, such as determining whether wrapping the magnets in aluminum foil
changes their magnetic property, or whether magnets change their strenght when they are very cold (straight out of the freezer).
The magnetic force gets weaker with distance. This is related to the way the field spreads out, as suggested by the magnetic field maps you made in the
previous unit.
Determine the range of the magnetic force for one through four magnets, and
make a graph of the results.