How Does the Electric Pencil Work?
Our electric pencil operates on the same general principle as Edison’s pen: the making and breaking of an electro- magnetic circuit. As you already know, electricity flowing through a conductor causes an electromagnetic field to form around that conductor. For this priceless bit of technical knowledge, we can thank the Danish physicist Hans Christian Oersted, who made the discovery back in 1819.BOLT BECOMES AN ELECTROMAGNET. To see how the principle of electromagnetism applies to the electric pencil, let’s look at the circuit diagram. Assume the pencil tip has just touched the flashlight. This completes the circuit and allows current to flow (current is considered to flow from + to-). At that precise instant, a magnetic field builds up around the coil, making the core (iron bolt) an electromagnet. The core, as a result, attracts the tip and starts pulling it away from the flashlight. However, even though the circuit is being opened, the current tries to keep flowing. So it begins arcing from the tip.
