Two students use a digital Tesla meter to investigate how the magnetic field strength of a small bar magnet varies with distance. They position the Tesla meter at different distances from one pole of the bar magnet along a ruler. The Tesla meter only shows readings as whole numbers (integers) in millitesla (mT\text{mT}mT). The table below shows their results: Distance (cm)Magnetic field strength (mT)1.0451.5202.0112.573.053.534.024.525.02\begin{array}{|c|c|} \hline \textbf{Distance (cm)} & \textbf{Magnetic field strength (mT)} \\ \hline 1.0 & 45 \\ 1.5 & 20 \\ 2.0 & 11 \\ 2.5 & 7 \\ 3.0 & 5 \\ 3.5 & 3 \\ 4.0 & 2 \\ 4.5 & 2 \\ 5.0 & 2 \\ \hline \end{array}Distance (cm)1.01.52.02.53.03.54.04.55.0Magnetic field strength (mT)452011753222 Each student displays the results as a different graph: * Graph A is a scatter plot of magnetic field strength against distance, with a smooth curve of best fit drawn through the points. * Graph B is a bar chart with discrete vertical bars representing the magnetic field strength for each measured distance.
Discuss which graph (Graph A or Graph B) is best for displaying this type of data.
Suggest how the students could improve the accuracy of their distance measurement.
Suggest why the reading on the Tesla meter remains constant at 2 mT2 \text{ mT}2 mT for the last three readings.
Different metal sheets can be used for magnetic shielding. The students modify their investigation to measure how effective different metal sheets are at shielding magnetic fields. They place a thin sheet of a test metal between the magnet and the Tesla meter. Describe how the students should control the variables in this new investigation.
