"No, nothing’s broken. They’re all in the holes."
"Is it a short circuit?"
Zhou Kai grabbed the multimeter, switched the dial to the resistance setting, and quickly measured a few nodes.
The numbers on the LCD screen jumped around.
"No short circuit. The resistance values are all within the normal range."
He turned to look at the transistor. "Did the transistor burn out?"
"It’s a cheap transistor. The leakage current might be too high, causing it to overheat and fail."
Wang Huashao let go, wiping his hand on his pant leg in frustration.
His palm was covered in sweat.
Zhou Kai was about to look for another transistor in the bottom of the case to replace it.
"Hold on. Don’t replace it yet."
Chen Zhuo’s voice cut them short.
He didn’t look at the scratch paper filled with formulas.
Nor did he check the circuit on the breadboard.
He walked to the middle of the workstation.
He held out a hand.
He slid his fingers under the edge of the black semiconductor cooling module.
His fingertips touched the downward-facing side of the module—the side pressed tightly against the surface of the wooden workstation.
Chen Zhuo held them there for two seconds.
Then he pulled his hand back.
"The ceramic plate on the bottom is warm."
Chen Zhuo looked at them.
Zhou Kai froze.
Wang Huashao didn’t understand either.
Chen Zhuo picked up the black cooling module and flipped it over.
The wooden tabletop underneath, having just been pressed down upon, held a faint residual warmth.
"It’s not a problem with the circuit."
He placed the cooling module back on the table.
"Thermoelectric generation, the Seebeck effect, requires a temperature gradient between the hot and cold ends."
"Wang Huashao has been using his body heat to warm the top ceramic plate."
"The heat is conducted downward through the semiconductor material."
"The cold end underneath is pressed tightly against this wooden table."
"Wood is a poor conductor of heat."
Chen Zhuo pointed at the tabletop.
"The heat can’t dissipate. It’s all accumulating at the bottom."
"Within ten seconds, the top and bottom sides of the cooling module reached thermal equilibrium."
"The top is one temperature, and the bottom is the same temperature."
"With no temperature difference, the potential difference instantly dropped to zero."
"That’s why the light went out."
The others stared at the black ceramic module.
A basic principle of physics stood like an invisible wall before them.
Thermoelectric generation doesn’t just need a heat source.
It needs a cold source that can continuously draw away heat and maintain a low temperature.
But in an examination hall with nothing but a wooden table, where were they supposed to find a cold source?
The time on the large screen changed to 01:05:00.
The hall was still buzzing with activity.
Other teams were still tearing their hair out over getting 0.5 volts.
Meanwhile, Chen Zhuo’s team had already reached the final lock on this system.
"We’ll make a cold source."
Without hesitating, Chen Zhuo gave the order.
He turned and walked toward the large, black metal case.
The bottom of the case was an aluminum alloy base plate, meant for reinforcement, held in place by several Phillips head screws.
"Wang Huashao, get a screwdriver and remove this base plate. Aluminum has a low specific heat capacity and good thermal conductivity."
Chen Zhuo pointed to the bottom of the case.
Wang Huashao immediately grabbed a screwdriver and started forcefully turning the screws on the bottom of the case.
"Zhou Kai, go to the restroom."
"Get a roll of paper towels, soak it completely with water, and don’t wring it out. Leave it dripping. Quick."
Chen Zhuo turned to He Gui.
"He Gui, please rearrange the circuit. Lengthen the red and black input leads; we need to reposition the cooling module."
A moment later, Zhou Kai came running back.
He was cupping a soggy mass of white paper towels. Water dripped down through his fingers, splashing onto the floor.
Wang Huashao had also removed the rectangular aluminum alloy base plate.
"Put it underneath," Chen Zhuo directed.
Wang Huashao laid the aluminum plate flat on the wooden tabletop.
Zhou Kai spread the water-soaked wad of paper towels over the aluminum plate.
Chen Zhuo picked up the semiconductor cooling module and pressed its cold end firmly onto the wet paper towels.
"Water evaporating at room temperature carries away a large amount of latent heat of vaporization."
Chen Zhuo looked at the simple, sandwich-like structure.
"This heat sink, made of wet paper towels and an aluminum plate, will force the cold end’s temperature to lock at room temperature, or even lower."
"This cold source will be enough to last through the ten-second test."
The system was reassembled.
The moisture in the paper towels slowly seeped out.
The aluminum plate conducted the ambient temperature.
The clock hit 00:55:00.
"Let’s try again." Chen Zhuo took a step back.
Wang Huashao vigorously rubbed his palms on his pant legs.
He took a deep breath.
Once again, he leaned forward and laid both palms flat on the hot end of the cooling module.
He pressed down hard.
Zhou Kai stared at the LED on the breadboard.
He Gui held his breath.
One second.
Two seconds.
Three seconds.
The light didn’t turn on.
Five seconds.
Ten seconds.
The small, transparent plastic bulb remained lifeless.
Not even the faintest glimmer of red light appeared inside.
"No reaction." Wang Huashao’s voice was starting to sound panicked.
He lifted his palms and pressed them down hard again, trying to increase the contact area.
Still nothing.
The multimeter reading didn’t even exceed 0.1 volts.
"Did the wet paper towel cause a short circuit?" Zhou Kai quickly checked the wiring at the edge of the cooling module.
No water had seeped in; the insulation was intact.
"Or did the transistor burn out earlier?" He Gui picked up the multimeter.
Chen Zhuo walked over.
He didn’t look at the circuit.
Instead, he reached out and grabbed Wang Huashao’s wrist.
He pressed his fingers against Wang Huashao’s palm.
Chen Zhuo’s brow furrowed slightly.
He let go.
"Your hands are too cold."
Wang Huashao was stunned.
He touched the back of his own hand.
A layer of cold sweat.
His fingers were icy, as if they’d been soaked in ice water.
Chen Zhuo looked at Zhou Kai.
"You try."
Zhou Kai immediately pressed his hands onto the cooling module.
Ten seconds passed.
The light still didn’t turn on.
Chen Zhuo touched Zhou Kai’s fingers.
Same thing.
Icy and slick with cold sweat.
Chen Zhuo didn’t bother checking the hands of He Gui or Miao Shian.
He knew the result would be the same.
This was no longer a physics problem.
It was a physiological one.
They had been under immense pressure, first from the six-hour individual competition yesterday, and now for over three hours in today’s noisy, competitive exam hall.
Zhou Kai was solving complex equations.
He Gui was winding delicate, nerve-wracking wires.
Wang Huashao was enduring an endless cycle of trial, error, and waiting.
Their bodies had been in a continuous state of high alert.
The sympathetic nervous system had taken complete control.
Adrenaline was flooding their systems.
To ensure blood supply to the brain and vital organs, their peripheral blood vessels constricted dramatically.
Blood circulation to their extremities had dropped to a minimum.
The more nervous they got, the more they wanted to win, the colder their hands became, and the more they produced cold sweat.
Right now, the temperature of Wang Huashao’s and Zhou Kai’s palms was insufficient.
Combined with the heat lost to the evaporating sweat, they were completely unable to provide a stable heat source.
The wet paper towels had successfully locked the cold end’s temperature.
But they had lost their only heat source.
The thermodynamic system had been constructed perfectly.
Yet it was defeated by the instinctive physiological response of the human body.
The time on the large screen jumped to 00:50:00.
Less than an hour left.
Wang Huashao paced anxiously, constantly rubbing his hands together, trying to generate heat through friction.
But the more anxious he got, the faster his heart beat, and the more cold sweat his palms produced.
The little bit of warmth he’d just rubbed into them would turn icy again in a matter of seconds.
Miao Shian took off his glasses and rubbed his dry eyes.
A sense of despair settled like a thick layer of dust over the workstation, which was cluttered with loose components.
All the pieces of the system’s puzzle were in place.
Yet the final piece had crumbled, and that piece was their own bodies.
Chen Zhuo stood by the table.
He looked at the dim light-emitting diode.
His fingers lightly traced the wood grain on the edge of the workstation.
All around them was the desperate clamor of a hundred other people.
The deadline was drawing closer, second by second.

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