Basics of Magnetism - Year 7 PDF Download

Introduction

• An invisible magnetic field is the region around a magnet where a force may be felt. It can be visualized using iron filings, emphasizing the importance of eye protection during this process.
• Using plotting compasses is a useful method to explore and understand the shape of a magnetic field.

Experimenting with magnets

• Magnetic fields are invisible. We need a way to reveal them to check their shape and investigate their properties so that we can better understand how they work and how we might use them.

A bar magnet

Method 1- iron filings

Iron filings are tiny bits of iron that can be sprinkled around the magnet. These will line up with the magnetic field, showing its shape.

• It can be challenging to remove the iron filings from a magnet, so place the magnet under a piece of paper to separate them.
• Sprinkle the iron filings carefully on top of the paper. Add them gradually to ensure a clear pattern.
• Gently tap the paper. This action causes the iron filings to 'jump,' aligning them with the magnetic field lines.
• Remember to visually document the patterns observed to keep a record of your findings.
• After completion, use a sheet of paper to transfer the iron filings back to their container and clean up any remaining residues.

Method 2- Using Plotting Compasses

The alternative technique to visualize a magnetic field involves employing a compass, a tool equipped with a magnetized needle that aligns with magnetic fields. The compass needle indicates the direction of the magnetic field surrounding any magnet.

• A compass, featuring a magnetized needle, aligns with the magnetic field.
• When working with relatively small magnets, miniature compasses known as plotting compasses can be beneficial.

Using Plotting Compasses to Show Magnetic Fields

• Step 1: Place your magnet in the center of your paper.
  
• Step 2: Place your plotting compass at one end of the magnet, slightly to the side.
  
• Step 3: Use a pencil to mark where the end of the needle points.
  
• Step 4: Move the compass so that the back of the needle is on your mark, then mark where the other end of the needle is now.
   
• Step 5: Repeat step 4 until you come to the other end of the magnet or reach the end of the paper.
  
• Step 6: Repeat from step 2, starting at a slightly different position at the end of the magnet
  
• Step 7: Join the marks (X) together
  
• Step 8: Keep repeating until you have marked out the magnetic field all around the magnet