Sarah Boyd offered marshmallows to the Niskayuna High School students.
These weren’t just any marshmallows, though. They were crunchy because Boyd, a graduate student at Rensselaer Polytechnic Institute, had dipped them in liquid nitrogen, making the treats hard.
“They’re better frozen,” she said.
Boyd wasn’t giving a cooking lesson; she was providing a physics lesson about molecular structure. She is part of Material Advantage, a group of RPI undergraduate and graduate students who give demonstrations at area schools to interest youths in the material sciences.
High school physics teacher Chris DeLano said material sciences is becoming a hot industry locally with the opening of the GlobalFoundries Fab 8 plant in Malta.
“They need people who can work with advanced materials,” he said.
Niskayuna physics students of varying abilities, including Advanced Placement, Regents and mastery level, were brought together for the special demonstration.
“What we teach is theory,” DeLano said. “This is giving them a little bit of practical applications.”
Boyd said material sciences is one of the most exciting fields right now and there are all sorts of uses for it in creating semiconductors, microelectronics and biomedical devices.
After a brief overview, students split into groups and watched six demonstrations.
Boyd also demonstrated how much a ball could bounce if it was placed in liquid nitrogen. The ball is made of polymers, which can be thought of as a chain of molecules. At higher temperatures, the molecules are excited and wiggle, creating more bounce. At lower and moderate temperatures, they are not as excited and lose their bounce.
Boyd pointed out a similar principle was at work when the Space Shuttle Challenger exploded after liftoff in 1986. A seal in its right solid rocket booster cracked because of the cold temperatures.
“Fuel was released, and it caused an explosion,” she said.
Another experiment involved adding salt to water and generating enough current to light a small bulb. RPI senior Karly Chester explained that adding the salt creates free electrons in a process known as “doping.”
“You’re creating ions that are positive and negative, so you can jump a charge across them,” she said.
Negative and positive ions are attracted to each other, which creates the electricity.
RPI student Peter Lezzi of Schenectady explained that materials scientists can change the chemical makeup of metals to create compounds that can conduct electricity more easily. “Metals conduct electricity better at low temperatures. Semiconductors conduct electricity better at higher temperatures,” he said.
RPI student Matt Kwan used Silly Putty to demonstrate the elasticity of the material. In this case, the speed at which it was pulled determined how much it could stretch.
“If we pull this very fast, we know that it snaps and it doesn’t stretch,” he said.
RPI student Heather Conway spoke about how fiber-optic cable works to deliver a television signal. The light hits the fiber-optic cable at an angle so it stays in there and doesn’t bounce out. Otherwise, she said, half the picture might disappear before it got to the TV.
In another demonstration, a piece of wire was twisted. It reverted to its previous shape after being dipped in hot water.
“I just find it cool that you could put it in the water and it could straighten out,” said Niskayuna senior Tricia Ryan, who plans to study nursing.
Fellow Niskayuna senior Bowen Zhang said he enjoyed the demonstrations and wants to study physics.
“It’s a pretty cool field,” he said.