“Grandpa?” 5 year-old Ben eagerly grabbed me one holiday, while the other kids played soccer.
“Yes Ben?” I replied, looking down at the blond bundle of thought.
Ben hesitated then found the right words. “How does electricity move without wires?”
His mother gave a familiar nod as such curious tenacity was routine.
“Well Ben,” I said not knowing what I’d say next. “When electricity flows in a wire, it…”
“No,” Ben asserted. “Not in a wire; without wires!”
Ben locked eyes with mine, one hand gripping a double-a battery, the other a Lego(R) creation with levers and cranks.
Experience told me it was time for an illustration.
“Let’s get paper and pencil.”
Off he went and returned quickly.
“Okay.” I drew a simple image of a battery, which he recognized from prior engineering collaboration. Then I drew a line representing a wire, a switch, and a light bulb all in one circuit loop.
“Remember this?” I pointed at the break in the circuit. “When you close this switch, the electricity flows throught the wire, through the light, and makes it glow.”
“I know grandpa, but what about…”
“Okay,” I interupted while moving my finger around the loop.
Ben followed carefully.
“When electricity, or charge, flows through a wire,” I continued, “it creates an invisible magnetic field around the wire.”
Ben studied my face again, his jaw dropped a little. “A magnetic field?”
“Or a force. If I open and close this switch again and again, it will create magnetic waves moving out away from the wire.”
I drew a similar nearby circuit with a smaller light, no switch, no battery, just a wire loop with small light.
“Now Ben, when you open and close this switch on the first circuit, it creates magnetic waves that go over to the other circuit, like the waves on the beach.”
I drew a series of arcs radiating across the paper.
“When the waves hit the new wire, it forces electricity to flow in the wire, and if the new circuit is sensitive enough, that electricity can be used to signal, or turn other things on and off.”
Ben looked at me, then at the paper, then at me again. I could almost hear the gears turning in his brain, or in this case, electrons orbiting his central processor.
“Let’s do it grandpa,” as he darted for his dad’s toolbox, “with real wire and batteries.”
“But don’t you want to play soccer?”
“No!” he said without explanation. “Let’s build a remote control.” He held up his Lego(R) machine, eyes as wide as the moon.