Draw a Circuit

Sketch an LED circuit using a graphite pencil. Copy the cupcake or create your own design.

things you will need

• Card or paper
• Pencil (make sure they are graphite)
• 9v battery
• 1 x LED
• Tape

Use the pencil to draw an outline of your design on the paper or card.

Fill in the lines

• Use the pencil to make the outline of your design wider.
• Mark one line positive (+) and the other negative (-).

Give it power

• Use the battery to close one of the gaps in your design.
• Place the positive terminal on the line that you marked + .
• Place the negative terminal on the line that you marked – .

Prepare the LED

• Make a note of which LED leg is the longest.
• Bend both legs of the LED.

• Place the battery on to the circuit.
• Hold the longest leg of the LED on the line marked + (positive) and the shortest leg on the line marked – (negative).
• Did the LED light-up? You may need to head somewhere a little dark to see it working.
• If your LED didn’t light up, first check that your battery and LED are the correct way around. Next, check for gaps in your circuit. If there are any gaps, grab your pencil and scribble over them.

Secure the LED

• Tape the longest leg to the line marked + (connected to the positive battery terminal).
• Tape the shortest leg to the line marked – (connected to the negative battery terminal)

Add some detail to your design using a crayon or felt tip pen.

Place the battery onto your circuit and get ready to showcase your design to friends and family.

So, what’s happening?

• The graphite in your pencil is an electrical conductor.
• Conductors are materials that allow electricity to pass through them.
• When you connect the two sides of your design with the battery you are creating a closed loop.
• Electricity will only flow when there are no gaps in its path and when there is a source of power (the battery).
• If you remove the battery the LED will turn off as you will have broken the circuit.

Time to experiment

Try some designs of different lengths and widths.

What do you notice about the brightness of the LED? Does it get dimmer the longer the length of the line?

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