Morse Code Telegraph
The principles of electricity and magnetism can be used to communicate - for example by using an electromagnet to make a Morse code transmitter.
The Morse code was invented as a way to transmit text over telegraph lines. In Morse code, each letter of the alphabet is encoded as a series of dots and dashes see Figure 1 on page 33 of the attachment. The shorter sequences of dots and dashes are assigned to the most frequently used letters. For example, the letter E is represented by a single dot, whereas the letter Q is represented by the sequence "dash-dash-dot-dash". This is one way of making the transmission as short as possible, since short sequences will occur more frequently than long sequences. In addition, common words are assigned their own shortcut sequences.
What You Need
Per group
- 2 blocks of wood
- Hammer
- Nail
- 2 alligator clips
- Battery holder and 4 AA batteries
- Adhesive tape
- Strip of cardboard 1 cm by 5 cm
- Magnet wire about 200 ft.
- Sandpaper
- Ruler
- Scissors
- Paper clip
Guide:
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe virtual outreach to youth.
What To Do
- Neatly wind the wire around the nail. Make at least 200 turns and leave a tail of about 10 cm of wire at each end. Make sure you leave at least 1 cm of exposed nail to be able to hammer it into the block of wood. See figure 2 on page 34 of the attachment.
- Using the sandpaper, sand the last 2 cm off each end of the wire, so the coating is scraped off or looks dull, if this has not already been done. See figure 3 on page 35 of the attachment.
- Place one block of wood on top of the other, with the front of the top block shifted about 5 cm from the other see Figure 4 on page 35 of the attachment. Tape them together.
- Hammer the nail into the lower block of wood until the head of the nail is 3 mm lower than the top of the upper block of wood. See figure 5 on page 36of the attachment.
- Cut a 1 cm by 5 cm strip of cardboard and tape it to the upper block. Attach the paper clip to the end of the cardboard. If you need to, reposition the cardboard or paper clip to ensure that the tip of the paper clip is just above the head of the nail . See figure 6 on page 36 of the attachment.
- Make sure the switch on the battery pack is off, and insert the four batteries into it
- Using the alligator clips, connect each of the wires from the battery pack to one end of the wire wound around the nail. Make sure to clip the alligator clips onto an exposed part of the wire.
- Before continuing, ensure your setup looks like the one illustrated on page 37 of the attachment.
- Turn the switch on the battery pack on. The paper clip should move towards the nail. Don't worry if the paper clip does not touch the nail.
- If the paper clip does not move, adjust the strip of cardboard or the paper clip so they are slightly closer to the nail.
- Turn the switch off. The paper clip should move away from the nail. If the paper clip is still stuck to the nail, adjust the strip of cardboard or the paper clip so they are slightly further apart.
- Caution! If you leave the switch on for too long, the batteries will drain.
Discovery
When the battery pack is switched on, the current from the batteries is free to circulate within the wire. The current goes around the nail and aligns the particles of the nail in such a way as to transform it into a magnet. The paper clip is drawn towards the nail each time the switch is on. The message you tap using the switch is then reproduced in the paper clip at the other end of the circuit.
Sending a message:
Remember that the point of creating a Morse code telegraph was to compare it with the cell phones your company develops. You now want to test your telegraph by sending a message to your colleague. Ask another student to assume the role of your colleague. First, write down a message in Morse code using dots and dashes see Figure 1 on page 33 of the attachment and then send your message to your colleague using your telegraph. Keep in mind the following:
To send a Morse code dot, turn the switch on for 1 second.
To send a Morse code dash, turn the switch on for 3 seconds.
Pause briefly between each letter so your colleague knows when a new letter is starting.
Your colleague will write down the dots and dashes as they are transmitted through the telegraph and then decode your message. This is how people communicated using electricity before the telephone was invented!
What's Happening?
When the battery pack is switched on, the current from the batteries is free to circulate within the wire. The current goes around the nail and aligns the particles of the nail in such a way as to transform it into a magnet. The paper clip is drawn towards the nail each time the switch is on. The message you tap using the switch is then reproduced in the paper clip at the other end of the circuit.
Sending a message:
Remember that the point of creating a Morse code telegraph was to compare it with the cell phones your company develops. You now want to test your telegraph by sending a message to your colleague. Ask another student to assume the role of your colleague. First, write down a message in Morse code using dots and dashes see Figure 1 on page 33 of the attachment and then send your message to your colleague using your telegraph. Keep in mind the following:
To send a Morse code dot, turn the switch on for 1 second.
To send a Morse code dash, turn the switch on for 3 seconds.
Pause briefly between each letter so your colleague knows when a new letter is starting.
Your colleague will write down the dots and dashes as they are transmitted through the telegraph and then decode your message. This is how people communicated using electricity before the telephone was invented!