# Edexcel IGCSE Physics: Double Science 复习笔记：6.1.4 Core Practical: Investigating Magnetic Fields

### Core Practical 12: Investigating Magnetic Fields

#### Aim of the Experiment

• To investigate the magnetic field pattern for a permanent bar magnet and between two bar magnets

#### Method

Step 1:

• Place the magnet on top of a piece of paper
• Draw a dot at one end of the magnet (near its corner)

Step 2:

• Place a plotting compass next to the dot, so that one end of the needle of the compass points away from the dot
• Use a pencil to draw a new dot at the other side of the compass needle

Step 3:

• Move the compass so that it points away from the new dot, and repeat the process above

Step 4:

• Keep repeating the previous process until there is a chain of dots going from one end of the magnet to the other
• Then remove the compass, and link the dots using a smooth curve – this will be the magnetic field line

Step 5:

• Repeat the whole process several times to create several other magnetic field lines

Step 6:

• Repeat the whole process for two bar magnets placed 5 cm apart first facing the same pole then facing opposite poles

#### Analysis of Results

• The magnetic field pattern for the single bar magnetic should look like this:

• The magnetic field pattern for two bar magnets should look like this:

#### Evaluating the Experiment

• Make sure the pencil you use is sharp to provide a clear and accurate drawing of the field lines
• Read the marker on the compass from above and not at an angle
• Allow the compasses to settle for a couple of seconds before taking the reading