Chapter 53: Morning Scroll and Copper Shavings

04:30. The alarm had not rung. His body clock woke first.

Lin Chen opened his eyes. Ceiling. Water stains. Their shape like an unfolded map. He did not move. He listened first. Corridor. Footsteps. Sparse. Far away. Boiler room. The low hum of the blower. Steady frequency.

He threw back the blanket. Cold air poured in. His skin tightened. Gooseflesh rose. The gauze on the sole of his foot rasped against the bedsheet. The split skin ached faintly. He sat up. Shifted his weight to his right leg. Kept the left suspended. No pressure on the wound.

He felt inside the pocket against his body. The ledger. Opened it. Pencil moving.

Day 32. 04:35. Awake.

Temperature: normal. Foot injury: dry, scabbed. Mild pain under pressure.

Funds: 0.05 yuan. Shortfall: 1.65 yuan.

Goal: 06:00 theory paper. Also complete the tools for practical work.

Backup plan: scrap depot. Morning market. Cardboard. Copper wire.

The pencil tip paused. He closed the book. Slid it back into his pocket.

He stood. Dressed. Movements light. Not enough to shake dust loose. Rubber boots on. Laces tight. Double-knotted. Canvas bag checked. Stationery. Graph paper. Homemade soldering-iron parts. Mercurochrome. Dried tangerine peel. Zipper pulled shut. Weight evenly balanced.

He pushed the door open. Locked it behind him. The corridor was empty. The sound-activated light had not come on. He walked along the wall. Light steps. Weight pitched forward. Stride length: thirty centimeters. Avoided the icy edges. The tread bit into the concrete floor. Made a faint crunching sound.

Stairwell. Cold wind pouring down. Carrying the smell of chalk dust and old wood. He went downstairs. Breathing steady. White mist spreading from his lips. Not lingering.

05:10. The athletic field. Heavy frost. Grass blades gone white. Step on them. Crisp crackle. The air dry and cold. A faint sting in the nasal passages. He jogged slowly around the track. Two laps. No speeding up. No slowing down. Kept his heart rate at one hundred ten a minute. Blood returned. Limbs warmed. The pain in the sole of his foot dulled.

05:30. Back to the dorm. Cold water. Piercing. Washed his face. The towel rough. Scraping his skin. Leaving red marks. He was awake.

He spread out fresh paper. Pencil. Ruler. Drew axes. Marked scales. No shading. No filling. The lines straight. Even. He closed his eyes. In his mind there were no curves. Only formulas. Ampère force. Lorentz force. Alternating current. Equivalent resistance. Three lines crossing in the dark. Not colliding. Not tangling. Each going forward on its own.

He opened his eyes. His gaze fell on the drawing. The first stroke came down. Steady. No tremor.

05:50. Out the door.

Examination room. Tiered classroom. Long tables. One meter apart. Deep scratches on the desktops. Grain exposed. On the blackboard was written: Electromagnetism Theory Paper (II). Time limit 100 minutes. Full score 100.

Lin Chen sat in the third row by the window. Fixed position. Neither too far nor too near.

He set the canvas bag by his feet. Took out his stationery. Two sharpened pencils. One eraser. One ruler. Three pads of scratch paper. Arranged them in order. No crossing. No overlap.

The papers were handed out. Rough stock. Strong smell of ink.

He turned the page. Read the questions. Did not start writing at once. First he skimmed the whole paper. Distribution of question types. Multiple choice. Fill-in-the-blank. Calculations. Final difficult problem. Difficulty gradient. Time allocation.

Multiple choice. Fifteen minutes. Fill-in. Twenty minutes. Calculations. Forty-five minutes. Final problem. Twenty minutes. Reserve. Ten minutes.

The pencil tip touched down. First question. Charged particle moving in a combined field. Electric force balanced by Lorentz force. Find the velocity. v = E/B. Direct choice.

Second question. Self-induction. The instant the switch opens, the coil produces an induced electromotive force. Opposes the decrease in current. The bulb flares, then goes out. Choice.

Third question. Effective value of alternating current. Sine wave. Peak value divided by root two. Calculate. Choice.

The pencil never stopped. No hesitation. No looking back. When he hit a snag, he circled it, marked it, skipped it. No entanglement.

Time passed. Only the dry rustle of pencil on paper. And the brittle snap of pages turning now and then. Someone sighed. Someone spun a pen. Someone cursed under his breath.

Lin Chen did not raise his head. Fingers steady. Scratch paper used by zones. Left side for setup. Right side for calculation. Blank space in the middle. For checking.

Second calculation problem. Electromagnetic induction. A rectangular coil rotating at constant speed in a uniform magnetic field. Find the instantaneous value of the induced electromotive force.

He wrote the magnetic flux first. Φ = BS cosθ. θ = ωt. Differentiate. e = -dΦ/dt = BSω sinωt.

Substitute the data. B = 0.5 T. S = 0.04 m². ω = 100π rad/s. Therefore e = 2π sin100πt.

Dimensional check. Volts. Correct. Boundary-value check. When t = 0, e = 0. Fits the neutral-plane logic. When t = T/4, e is maximal. Fits perpendicular cutting.

He wrote down the answer. Units. Significant figures. Checked. No error.

The pencil tip paused. He turned to the final problem. Capacitive circuit combined with electromagnetic induction. A metal rod sliding down inclined rails. The rails connected to a capacitor. Find the steady acceleration.

He frowned. Did not panic. Drew the force analysis. Component of gravity. Ampère force. Friction. Wrote Newton’s second law.

Ampère force F = BIL. I = dq/dt. q = CU. U = BLv. Therefore I = CBL(dv/dt) = CBLa.

Substitute. F = B²L²Ca.

Equation closed. mg sinθ - μmg cosθ - B²L²Ca = ma.

Solve for a. Substitute the numbers. Dimensional check. Meters per second squared. Correct.

He wrote out the derivation. Steps clear. Logic closed. No skipped steps. No omissions.

Time. 07:40.

“Pens down. Hand in your papers.”

The proctor collected the exams. Paper rubbing against paper. Dense and continuous.

Lin Chen set down his pencil. His fingers were slightly stiff. Red marks pressed into the pads. He flexed his wrist. The joint gave a faint click.

He stood. Handed in the paper. Turned. Left.

The corridor was cold. Wind surged up from the stairwell. Carrying the smell of chalk dust and old wood.

Back to the dorm. He pushed the door open. Locked it. Set the canvas bag on the bed. Movements light.

He spread open the ledger. Pencil moving.

Day 32. 08:05. Theory Paper (II) finished.

Estimated lost points: 1 multiple-choice question (misjudged deflection direction in a combined field). 1 fill-in question (careless error in effective-value calculation).

Estimated score: 86–89.

Lesson: transient processes in capacitive circuits need reinforcement. Must become fluent in the link between dq/dt and acceleration a.

Funds: 0.05. Shortfall: 1.65.

The pencil tip paused. He closed the ledger.

He stood. Went out. Stride length thirty centimeters. Not stepping on the edges.

08:20. Logistics scrap depot. The iron gate half open.

Boss Sun sat beside a coal stove. Steelyard in hand. The graduations on the rod worn down. The copper pan dull. Coals glowing dark red. White vapor breathing from the stovepipe.

“Boy Lin. Back again.”

“Cardboard. Old newspapers. Draft paper.”

Old Sun nodded. Took them. Put them on the scale. The sliding weight moved. The mark stopped.

“Three jin, two liang. Old rate. Four fen a jin. Twelve fen.”

Lin Chen shook his head. “Not enough.”

Old Sun raised his brows. “Rules are rules. Paper is paper. No watering it.”

Lin Chen did not argue. From the side pocket of the canvas bag he took out dried tangerine peel. Wrapped in old newspaper. Moisture-proof. A faint scent escaping.

“Tangerine peel. Sun-dried. Deodorizing. Medicinal. Two jin.”

Old Sun took it. Crushed a piece. Smelled it. Nodded. “Good quality. Pharmacy will take it. Eight fen a jin. Sixteen fen.”

Total. Twenty-eight fen.

Lin Chen reached into the pocket against his body. Took out a five-fen coin. Set it on the table.

“Round it up. Thirty-three fen. Trade for copper wire. Resistors. Or give me change.”

Old Sun sighed. Pulled open a drawer. Rummaged. Took out half a length of copper wire, 1.5 millimeters in diameter, about thirty centimeters long, surface oxidized to a dull dark red. Then he found three resistors. The color bands were blurred, but still readable.

“Copper wire. Scrap copper price. One yuan twenty a jin. This piece is about one liang. Twelve fen. Resistors, salvaged parts. Counted by piece. Five fen each. Three of them, fifteen fen. Total twenty-seven fen. I owe you six fen.”

Lin Chen took them. Copper wire. Resistors. Coins. Weighed them in his hand. Light. But heavy.

Funds. 0.05 + 0.28 + 0.06 = 0.39 yuan.

Shortfall. 1.65 - 0.39 = 1.26 yuan.

He closed his eyes. In his mind there were no formulas. Only circuit diagrams. Temperature. Time. Solder melting. Solidifying.

He opened his eyes. His gaze fell on the corner of the scrap depot. The shell of an old radio. Sheet metal. Rust stains. Nearby lay several discarded heating wires. Diameter 0.3 millimeter. Uneven lengths.

He walked over. Squatted. Picked them up. Three pieces. Total length about forty centimeters. Resistivity known. Power P = U²/R. If connected to a 12V DC supply, current limiting would be needed in series. But there was no 220V socket in the exam room. Only a 12V DC source.

He shook his head. Abandoned the idea. Voltage mismatch. Insufficient power. The soldering tip would not reach 350°C.

He took out his old notebook. A blank page. Pencil moving.

Revised substitute plan:

1. Copper wire acquired. Can serve as base material for the soldering tip. Needs polishing.

2. Resistors acquired. Missing 10Ω/20W. Existing ones are 100Ω/2W. Unusable.

3. Current-limiting resistor still needed.

4. Funding gap: 1.26 yuan.

Countermeasure: before the morning practical, help Old Zhao sort the storeroom in exchange for labor pay. Or find a classmate from Group A to split an order.

The pencil tip paused. He closed the notebook. His fingers tightened. The page edges curled. He shoved it to the bottom of the bag and pinned it down.

He stood and headed for the storeroom. Empty corridor. Footsteps echoing. Cold.

08:50. Logistics warehouse. Iron door half ajar.

The manager, Old Zhao, sat beside a coal stove wrapped in a military overcoat. Ledger in hand. Coals glowing dark red. White vapor from the stovepipe.

“Boy Lin. Borrowing tools?”

“Sorting the storeroom. For labor pay. Or change.”

Old Zhao raised his brows and set down the ledger. “Storeroom’s a mess. Needs sorting. Resistors. Capacitors. Diodes. Categorize them. Label them. Two hours. Two yuan. Cash immediately.”

Lin Chen nodded. “Deal.”

He turned and went in. Cold air flooded over him. Carrying the smell of machine oil and old rubber. A faint sting in his nose. But it sharpened him.

Shelves. Disorderly. Components scattered. No labels. Deep scratches on the tabletop. Wood grain exposed.

He opened the canvas bag. Took out old newspaper. Spread it on the floor. Sorted by category. Resistors by color band. Capacitors by capacitance. Diodes by polarity. Movements steady. No tremor. Not touching anyone else’s things.

Time passed. Only the soft click of components striking one another. And low, compressed breathing. Someone coughed. Someone turned pages.

Lin Chen did not raise his head. Fingers steady. Sorting. Labeling. Recording. Quantity. Specification. Location.

Two hours. 10:50.

Old Zhao came over. Checked against the list. No mistake. Nodded.

“Two yuan. Cash now.”

Lin Chen took them. Two one-yuan notes. Edges worn, but flat.

Funds. 0.39 + 2.00 = 2.39 yuan.

Shortfall. 1.65 - 2.39 = -0.74 yuan. Surplus.

He closed his eyes. In his mind there were no formulas. Only circuit diagrams. Temperature. Time. Solder melting. Solidifying. Three lines crossing in the dark. Not colliding. Not tangling. Each going forward on its own.

He opened his eyes. His gaze fell on the corner of the warehouse. Old wire-wound resistors. 10Ω/20W. Three of them. Marked price: forty fen each.

He walked over. Picked one up. Checked the color bands. Brown, black, black, gold. Resistance 10Ω. Power 20W. Correct.

“I’ll buy all three.”

Old Zhao wrote it down. “One yuan twenty. Eighty fen back to you.”

Lin Chen took them. Resistors. Coins. Weighed them in his hand. Light. But heavy.

Funds. 2.39 - 1.20 = 1.19 yuan. Surplus.

He turned and left. Stride length thirty centimeters. Not stepping on the edges.

Back to the dorm. He pushed the door open. Locked it. Set the canvas bag on the bed. Movements light.

He spread open the ledger. Pencil moving.

Day 32. 11:10. Materials complete.

Copper wire. 0.30 m. Resistors. 10Ω/20W × 3. Rosin. Solid block. Solder wire. Leaded 63/37.

Funds: 1.19 yuan. Surplus.

Next step: assembly. Testing. Preheating.

The pencil tip paused. He closed the ledger.

He stood and went to the washroom. Cold water. Piercing. Washed his face. The towel rough, scraping his skin, leaving red marks. It did not hurt. He was awake.

Back in the room. He spread out fresh paper. Sketched.

Soldering tip. Copper wire, 1.5 millimeters in diameter, thirty centimeters long. One end ground into a bevel. A hole drilled in the other end. Heating wire threaded through. Heating wire wound around the copper. Wrapped in insulating mica sheet. Connected to a 12V power supply. 10Ω/20W wire-wound resistor in series.

He calculated the power. Resistance of the copper wire negligible. A series current-limiting resistor required. R = U²/P. Let P = 15W. R = 12²/15 = 9.6Ω. Choose a 10Ω/20W wire-wound resistor. Suitable.

Feasible.

He took out the parts. Arranged them in order. No panic. No rushing. Not touching anyone else’s things.

He picked up the copper wire. Polished it with sandpaper. The bevel smooth. No oxide layer. Drilled the hole. Threaded in the heating wire. Wound it tight. Wrapped it with mica sheet. Fixed it with insulating tape. Connected to the 12V supply. 10Ω resistor in series.

Power on. The copper wire heated. Faintly red. He brought the rosin block close. It melted. A slight white smoke rose. The smell was sharp. But familiar.

He picked up the solder wire. Leaded 63/37. Melting point 183°C. Touched it to the joint, not the iron. Three seconds. The solder melted. He withdrew. It solidified.

The solder joint. Bright. Conical. No burrs. Acceptable.

Stopwatch. Tick. Tick.

Countdown. Twenty-nine minutes and fifty-nine seconds.

He closed his eyes. In his mind there were no formulas. Only temperature. Time. Solder melting. Solidifying. Three lines crossing in the dark. Not colliding. Not tangling. Each going forward on its own.

He opened his eyes. His fingers came down. Movements steady. No tremor.

Old Li’s gaze swept over him. Paused. No comment. Only the stopwatch. Tick. Tick.

Outside the window. The sky dark. Clouds hanging low. No snow yet. Wind slipping through the cracks with a low whine.

The broadcast speaker. Static. Buzzing. Old Li’s voice, rough with interference, piercing the walls.

“Additional practical this afternoon at two. Soldering. Bring your own tools. Rules unchanged. Those without them may borrow. Deposit deducted. Limit two times per day. Overtime billed by the hour. Also, notice from the Municipal Education Committee: this practical adds a ‘blind soldering’ segment. Eyes closed. Judge by feel. Qualified joint, bonus points. Unqualified joint, points deducted. Not counted in the total score, but it affects the final rating.”

The current cut. Silence in the dorm.

Lin Chen opened his eyes. His gaze fell on the side pocket of the canvas bag. Dried tangerine peel. Old newspaper. He reached into the pocket against his body. Receipt. Red stamp. Fifty yuan. Paid already. But the road was not smooth. Soldering, he understood. Blind soldering, he had not practiced. Graph paper, he still needed to draw. Curves, he still needed to calculate. Time, he still had to squeeze out.

He stood and went to the washroom. Cold water. Piercing. Washed his face. The towel rough, scraping his skin, leaving red marks. It did not hurt. He was awake. Back in the room. He spread out fresh graph paper. Pencil. Ruler. Drew axes. Marked scales. No shading. No filling. The lines straight. Even. He closed his eyes. In his mind there were no curves. Only solder joints. Temperature. Time. Solder melting. Solidifying. Three lines crossing in the dark. Not colliding. Not tangling. Each going forward on its own.

He opened his eyes. His gaze fell on the paper. The first stroke came down. Steady. No tremor.

Coordinate axes. Horizontal axis: load current. Vertical axis: output voltage. Origin. Zero point. Scale. Each square 0.1A, 0.1V. He calculated. No-load 5.0V. Full-load 4.95V. Voltage drop 0.05V. Linear. Negative slope. He drew the line. No break. No kink. Pencil dust fell on the paper. He erased lightly. No trace left.

His sole hurt. He changed posture. Shifted his weight to the right leg. Kept the left suspended. No pressure on the wound. His fingers were stiff with cold. He breathed on them. White mist scattered. Kept drawing.

Outside the window. The wind stopped. The snow grains turned finer. Tapping against the glass with soft pattering clicks. Everything flattened smooth. Nothing left but white. And cold.

Afternoon. Two o’clock. Additional practical.

He closed his eyes. Slept. But his hand was moving. On the bedsheet, his fingertips unconsciously traced a circuit diagram. Power source. Current limiting. Load. Feedback. Node. Loop. Ground. The lines straight. Even. No tremor.

Tick. Tick.