Chapter 113: The Principle of a Closed Circuit

Wednesday evening, a rental house in the suburbs.

After finishing dinner and cleaning up, Lin Xuan pushed aside the solid wood coffee table, clearing the large wool carpet in the center of the living room.

The two sat cross-legged facing each other.

The teacher had assigned a new homework task. Reading novels every day, the library is vast, ttk. tw enjoy anytime

Xiao Sizi pulled out a folded A4 sheet from her pink schoolbag.

Lin Xuan took it and unfolded the paper.

Printed on the paper were the science practice requirements for first grade at Shi Diyi Shiyan Xiaoxue, stating that parents must help assemble the most basic Closed Circuit model using unused old items or simple electronic components.

After reading it, Lin Xuan placed the paper on the side table at the edge of the carpet.

He stood up, walked to the entrance hall, and brought out a gray toolbox.

Returning to the carpet, he unfastened the metal lock and lifted the lid.

Inside were two No. 5 dry batteries with blue backgrounds and white lettering, along with several red and black wires equipped with metal clip terminals.

There was a red plastic button switch no larger than a fingernail, and a miniature Glass bulb with a base featuring brass threads.

Lin Xuan placed each item one by one onto the carpet.

Xiao Sizi leaned in and fiddled with the miniature bulb.

The Glass casing was exceptionally thin.

Inside was sealed a coiled metal filament as fine as a hair.

"Brother Lin Xuan, in the Great Tang, lamps were lit by wicks absorbing tung oil, then ignited with a fire starter," Xiao Sizi said, holding the small bulb and examining the ceiling light in the living room closely.

"This Glazed Ware sphere contains not a drop of oil paste; with just these few metal wires, how does it burn out light?"

"Modern people do not need open flames."

Lin Xuan reached into the bottom layer of the toolbox and pulled out a wire stripper with a yellow handle.

He selected a red wire and clamped the stripper jaws two centimeters from the wire's end.

He pressed his wrist down, closing the handles together.

Gripping with his knuckles, he pulled outward, and a section of red insulation sheath came off.

Dozens of intertwined purple-copper-colored metal filaments inside were exposed.

Lin Xuan held both ends of the wire and handed them to Xiao Sizi.

"Feel it; the outer plastic isolates external things, while the purple copper inside serves to lay the path."

Xiao Sizi extended her finger, her fingertip brushing against the rough copper filaments.

It felt somewhat prickly to the touch.

"Lay the path?" Xiao Sizi looked up, confusion in her eyes. "This wire is clearly solid; what is supposed to pass through it?"

Lin Xuan set down the wire stripper and picked up another dry battery.

He held the battery vertically between two fingers, gripping its top and bottom ends.

"Inside is sealed a particularly restless energy we call electricity."

Lin Xuan pointed to the raised metal cap at the top of the battery.

"You can think of this battery as a high-altitude water tower filled with water, and this copper wire is the hollow pipe connected to the tower's base."

Xiao Sizi nodded thoughtfully.

Lin Xuan picked up the red wire.

He lightly touched one end to the battery's positive terminal, while pulling the other end toward the small bulb.

"Once the copper wire connects, the water in the tower will rush down the pipe."

"The massive impact force will forcibly pierce the bulb's core; constant, frantic friction will generate heat, and finally, light will burst forth."

Xiao Sizi understood the logic of this explanation.

"If the water keeps flowing and flowing until it runs dry, either spilling into the soil, wouldn't the light then go out?" she countered.

Hearing this, Lin Xuan smiled and casually picked up a black wire.

"Modern physics places the utmost importance on rules."

Lin Xuan touched one end of the black wire to the other side of the bulb, then pulled it back to the flat negative terminal at the battery's base.

"After the water rushes through the bulb, it must absolutely not be allowed to flow randomly; use this black wire as a return pipe to guide the water that rushed out back along its original path to the water tower's base."

Lin Xuan raised one index finger and drew a complete circle in the air.

"Flow out, circle around, and return to the starting point."

"This self-sustaining set of rules is called a Closed Circuit in modern terms."

Xiao Sizi's eyes brightened slightly.

The Great Tang's Book of Changes emphasizes the cycle of the Heavenly Dao, repeating endlessly and generating life ceaselessly.

This seemingly crude explanation of physics strangely aligned perfectly with the highest philosophy spoken by ancient sages.

"I understand."

Xiao Sizi put down the bulb she was holding and reached for the wire stripper.

She selected an unstripped black wire and, mimicking Lin Xuan's earlier action, aligned the jaws with the wire's end.

The little girl's hand strength was not yet sufficient.

She pressed her lips tightly together, gripping the yellow plastic handle with both hands, and pressed down hard.

A few very fine blue veins bulged on the back of her hand as she pulled backward with all her might.

The black sheath was torn off, and the purple copper filaments inside instantly splayed out.

"Next step, wrap it by hand; ensure the copper filaments cling tightly to the metal contact points, leaving no gaps whatsoever."

Lin Xuan gave instructions from the side, not reaching out to help again.

The expression on Xiao Sizi's face also became exceptionally serious and earnest.

When the craftsmen of the Great Tang Directorate of Imperial Works crafted royal artifacts, they placed the utmost importance on mortise-and-tenon joints fitting together tightly.

The interfaces were seamless, with not a single gap.

The seriousness with which she now manipulated these few strands of purple copper wire was even more cautious and careful than when the Minister of Works inspected sacrificial vessels.

Using her fingernail to lift the tiny copper strands, she slowly twisted them into a single thin cord.

Round and round, winding very slowly around the brass threads at the base of the small light bulb.

After winding three turns, she pressed down firmly with the pad of her thumb.

Then she took the alligator clip with the red wire, pinched open the spring-loaded teeth with her thumb and forefinger, and clipped it onto the positive terminal of the battery.

After connecting each node, she would pinch the wire end and pull it twice in the opposite direction to confirm the metal connector had not loosened.

The entire process was very tedious, and the progress moved very slowly.

But from start to finish, not a single mistake or omission occurred.

In the end, only that red plastic switch remained on the carpet.

On either side of the switch extended a metal washer with a small hole.

Xiao Sizi threaded the ends of the two wires, serving respectively as the inlet and outlet, one by one through the small holes mentioned earlier.

Afterwards, she folded and knotted them, finally twisting them tightly into a shape like a twisted dough stick.

The laying work was now complete.

Two dry-cell batteries were arranged in series.

The red and black wires wove through them, connecting the light bulb and the switch together.

All the components on the carpet formed a very standard basic physical closed circuit.

Lin Xuan supported his knees with both hands and stood up from the carpet.

He stepped back half a pace, completely yielding the core position of the operation.

In the center of the vast carpet remained only this model built from metal and chemical materials.

And the Princess of Great Tang, sitting upright.

"All the water pipes are connected, but the gate in the middle is still stuck," Lin Xuan said, pointing to the red plastic piece in the middle of the circuit.

Then he extended his finger and pressed down on that red plastic tab.

Click.

A very faint crisp sound.

As the tab was pressed, the metal contacts closed inside the plastic casing.

The water gate opened.