Read Online Twistor by Gene; John; Wolfe Cramer - Free Book Online Page B
Authors: Gene; John; Wolfe Cramer
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hypothesis of knowledge, a thing to be argued in schools, a thing floating in the clouds, in endless logic vortices, 'til we try and fix it.
Thomas Carlyle
(1795â1881)
5
Thursday Morning, October 7
A bleary-eyed David Harrison looked out at the upward-sloping sea of student faces, then put the last transparency of his lecture on the overhead projector and hammered on the final concept concerning capacitance and energy storage. Some of the students were watching attentively, some flipping notebook pages, some yawning or reading newspapers at the back of the two-hundred-seat lecture hall. He had been teaching Allan's Physics 122 class all week, and he noticed that he was developing something of a fan club. The three attractive young ladies in the second row were sending him messages of dewy interest and anticipation. Good, that means they're awake, he thought.
He glanced at the large wall clock at the rear of the sloping theaterlike classroom. The time was 9:09 A.M., still eleven more minutes before the bell. Time for the demo, he thought, and walked behind the slablike lecture demonstration table. He pulled the heavy glass Leyden jar capacitor onto the aluminum sheet next to the department's antique Wimshurst machine.
The Wimshurst machine was a large electrostatic charging device straight out of the nineteenth century, a thing of tinfoil and turning glass plates and tinsel brushes and balls and cranks and round leather sewing-machine belts. As he turned the crank, the twin glass plates rotated in opposite directions, and between the silvery ball electrodes the apparatus produced a fat blue spark. The spark was accompanied by a curiously satisfying
Fwap!,
and a sharp ozone smell. A dozen bored faces turned to see what was going on. The 'fans' clapped with delight and smiled.
'Now,' said David, 'we're going to have a little demonstration that may teach us something about capacitance and energy storage. This big object is called a Leyden jar capacitor, and it's just like the one described in your book. It has cup-shaped metal conductors on the inside and outside, kept apart by the jar-shaped glass insulator. The insulator is quite thick, and it can hold many thousands of volts without electrical breakdown. Now I'm going to put a big electrical charge on it . . . ' He paused, leering at the class and beetling his eyebrows. ' . . . with this Wimshurst machine, which I have borrowed from Dr Frankenstein's laboratory deep in the Physics Hall basement,' he added, using his best Karloff imitation. That got a laugh.
'We're going to try and learn something about stored energy,' he continued, resuming his normal voice. He stopped cranking and picked up a long insulated rod supporting a C-shaped conductor that ended in two shiny balls. He held the C across the terminals of the Leyden jar.
Fwap!!
went the spark as he shorted the capacitor. 'See,' he said, ' I can store lots of energy in this capacitor because it holds a large voltage and has a big plate area. Now watch this one.' He turned the crank again and heard a satisfying sizzling noise as the Wimshurst machine again charged the device. 'This time, inspired by the work of Dr Frankenstein, we are going to dissect our patient,' said David, mugging a demented grin. The fans giggled.
As he turned to get the other insulated rod, he spotted Vickie standing just outside the exit door of the lecture hall, watching. Uh-oh, he thought to himself. For the first time in recent memory, he was not pleased to see her. Using the pair of insulated rods, he disconnected the large juglike capacitor from the machine, pushed it down the table to a second grounded plate, and grasped its metallic outer sheath by a projecting handle. This is a special kind of Leyden jar capacitor. It comes apart,' he said as he grasped an insulated handle on the inner conductor and pulled. The inner electrode, a blunt cylindrical piece of metal that fitted snugly into the interior of the jarlike glass
Thomas Carlyle
(1795â1881)
5
Thursday Morning, October 7
A bleary-eyed David Harrison looked out at the upward-sloping sea of student faces, then put the last transparency of his lecture on the overhead projector and hammered on the final concept concerning capacitance and energy storage. Some of the students were watching attentively, some flipping notebook pages, some yawning or reading newspapers at the back of the two-hundred-seat lecture hall. He had been teaching Allan's Physics 122 class all week, and he noticed that he was developing something of a fan club. The three attractive young ladies in the second row were sending him messages of dewy interest and anticipation. Good, that means they're awake, he thought.
He glanced at the large wall clock at the rear of the sloping theaterlike classroom. The time was 9:09 A.M., still eleven more minutes before the bell. Time for the demo, he thought, and walked behind the slablike lecture demonstration table. He pulled the heavy glass Leyden jar capacitor onto the aluminum sheet next to the department's antique Wimshurst machine.
The Wimshurst machine was a large electrostatic charging device straight out of the nineteenth century, a thing of tinfoil and turning glass plates and tinsel brushes and balls and cranks and round leather sewing-machine belts. As he turned the crank, the twin glass plates rotated in opposite directions, and between the silvery ball electrodes the apparatus produced a fat blue spark. The spark was accompanied by a curiously satisfying
Fwap!,
and a sharp ozone smell. A dozen bored faces turned to see what was going on. The 'fans' clapped with delight and smiled.
'Now,' said David, 'we're going to have a little demonstration that may teach us something about capacitance and energy storage. This big object is called a Leyden jar capacitor, and it's just like the one described in your book. It has cup-shaped metal conductors on the inside and outside, kept apart by the jar-shaped glass insulator. The insulator is quite thick, and it can hold many thousands of volts without electrical breakdown. Now I'm going to put a big electrical charge on it . . . ' He paused, leering at the class and beetling his eyebrows. ' . . . with this Wimshurst machine, which I have borrowed from Dr Frankenstein's laboratory deep in the Physics Hall basement,' he added, using his best Karloff imitation. That got a laugh.
'We're going to try and learn something about stored energy,' he continued, resuming his normal voice. He stopped cranking and picked up a long insulated rod supporting a C-shaped conductor that ended in two shiny balls. He held the C across the terminals of the Leyden jar.
Fwap!!
went the spark as he shorted the capacitor. 'See,' he said, ' I can store lots of energy in this capacitor because it holds a large voltage and has a big plate area. Now watch this one.' He turned the crank again and heard a satisfying sizzling noise as the Wimshurst machine again charged the device. 'This time, inspired by the work of Dr Frankenstein, we are going to dissect our patient,' said David, mugging a demented grin. The fans giggled.
As he turned to get the other insulated rod, he spotted Vickie standing just outside the exit door of the lecture hall, watching. Uh-oh, he thought to himself. For the first time in recent memory, he was not pleased to see her. Using the pair of insulated rods, he disconnected the large juglike capacitor from the machine, pushed it down the table to a second grounded plate, and grasped its metallic outer sheath by a projecting handle. This is a special kind of Leyden jar capacitor. It comes apart,' he said as he grasped an insulated handle on the inner conductor and pulled. The inner electrode, a blunt cylindrical piece of metal that fitted snugly into the interior of the jarlike glass