Biot-Savart Wire-Loop Magnetic Field Mapping
An engaging, screen-free learning activity that builds real-world creativity and critical thinking for kids aged 7 to 9.
Materials Needed
- • Insulated copper hookup wire (20–22 gauge) (1 meter)
- • 1.5V D-cell alkaline battery (1 unit)
- • Small magnetic plotting compass (clear base) (1 unit)
- • White cardboard sheet (approx. 20x20 cm) (1 sheet)
- • Pencil and electrical tape (1 set)
Pro Tips
- → Punch a vertical wire through the center of a horizontal white cardboard sheet.
- → Place small compasses on the cardboard around the wire; when current flows, the needles align into a circle around the wire.
- → Reverse the positive and negative battery connections: the compass needles instantly flip 180 degrees in response.
Safety First
Disconnect battery leads after 5 seconds of testing to avoid overheating the wire and battery.
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Step-by-Step Instructions
Step 1
Punch a small hole in the center of a flat white cardboard square and thread a vertical copper wire straight through.
Step 2
Place a small pocket compass on the cardboard 2 cm away from the wire and note the baseline Earth-North direction.
Step 3
Connect the wire leads across a D-cell battery for 5 seconds and plot the direction the compass needle turns with a pencil arrow.
Step 4
Move the compass in a circle around the wire to plot arrows at 8 points, connecting them into a circular magnetic field line.