Transcript: Newton's Rings | Jul 09, 1990

(music plays)

Outside a diner, a man reads the paper, another man juggles and a magician plays tricks. The name “The science Café” appears in neon lights on one of the windows. Inside, the waitress shows a menu that reads “The Science Café proudly offers food for thought. Science demonstration from Ontario Science Centre. Newton’s Rings. Presented by Peter Harris. Producer and director: Michael Kushner. Researcher: Lisa-Ann Dunley.”

A caption reads “Peter Harris. Ontario Science Centre.”

Peter is in his forties, with very short black hair and a beard. He wears glasses, blue trousers and a blue polo T-shirt.

He stands by a table with a flask, a plastic tray with soapy water, a giant bubble wand and a dust bin on it.

He says HERE AT THE SCIENCE CENTRE,
BUBBLES ARE MORE THAN JUST FUN.
I'M SURE YOU'VE ALL THE
EXPERIENCE WHEN YOU WERE
YOUNGER WHERE YOU'VE
ACTUALLY PLAYED WITH BUBBLES.
BUT AS YOU GET OLDER, BUBBLES
BECOME A USEFUL TOOL FOR
HELPING TO EXPLAIN WHAT'S
HAPPENING IN THE PHYSICAL WORLD.
NOW, WHAT I INTEND TO DO TODAY
IS TALK A LITTLE BIT ABOUT
THE COLOURS THAT YOU
OBSERVE ON A SOAP FILM.

He holds the giant bubble wand up against the light to show the different colors on the soap film.

He says WHEN YOU ARE OUTSIDE AFTER A
RAINSTORM, OFTEN YOU'LL SEE
COLOURS AS IF THERE'S
A RAINBOW ON THE ROAD.
AND WHAT'S HAPPENING THERE IS
THAT YOU'VE GOT VERY, VERY
THIN FILMS OF OIL AND GAS.
SOAP FILMS PROVIDE MUCH THE
SAME SORT OF CIRCUMSTANCE.
WHAT WE'VE GOT IS A VERY,
VERY THIN FILM OF SOAP.
LIGHT IS HITTING THIS FILM,
REFLECTING BACK AT OUR EYES
AND PRODUCING THE
COLOURS THAT WE SEE.
NOW, WHAT I'M GOING TO DO IS
MAKE A BUBBLE WHICH HAS A
CLOUD INSIDE OF IT.
WHAT I'VE GOT IS A FLASK OF
HOT WATER, AND TO THE FLASK
I'LL ADD SOME LIQUID NITROGEN,
WHICH IS AT A TEMPERATURE
OF MINUS 196 DEGREES CELSIUS.
AS I ADD THE LIQUID NITROGEN
TO THE HOT WATER, THE WATER
VAPOUR WILL BE FROZEN,
AND AS THIS HAPPENS,
WE CREATE A CLOUD.

He dips a funnel in the soapy solution and places it upside down on the flask. A big white bubble generates.

He says AS I ADD A SOAP FILM TO THIS,
JUST OBSERVE WHAT HAPPENS.
SO THE SOAP FILM IS ON THE
END OF THE FUNNEL HERE.
THE BUBBLE FILLS WITH A CLOUD.
WHAT YOU'LL NOTICE INITIALLY
IS THAT THE COLOURS SEEM TO BE
FLOWING EVERY WHICH WAY.
IT'S AS IF IT'S QUITE RANDOM.
WE'VE GOT DIFFERENT
THICKNESSES OF SOAP FILM
ON THE WHOLE BUBBLE.
IF WE CONSIDER HOW LIGHT
IS HITTING THE BUBBLE,
WHAT WE'D FIND IS THAT THE
LIGHT IS IN THE FORM OF WAVES.
THIS IS ONE MODEL FOR THINKING
ABOUT HOW LIGHT BEHAVES.
IF YOU THREW A ROCK IN A POND,
YOU'D SEE A NUMBER OF RIPPLES
COMING AWAY FROM WHERE
THE ROCK HIT THE WATER.

A fast clip shows images of a ripple tank.

He says IF YOU WERE TO THROW ANOTHER
ROCK, RIGHT BESIDE THE FIRST,
WHAT YOU'D FIND IS THAT YOU
HAVE ANOTHER RIPPLE PATTERN.
AND WHEN THE TWO RIPPLE
PATTERNS COLLIDE, WE SEE
THAT THEY INTERFERE
WITH EACH OTHER.
WHEN IT HAPPENS ON A SOAP
FILM, WITH WAVES OF LIGHT,
SOME WAVES WILL REFLECT OFF
THE FRONT SURFACE, AND OTHER
WAVES REFLECT OFF
THE BACK SURFACE.

A graph appears on screen representing the way a ray of light reflects on the inner and outer surface of a soap bubble, creating interference patterns.

Peter says THE WAVES COLLIDE.
THIS INTERFERENCE IS PERCEIVED
BY OUR EYES AS LIGHT OF
DIFFERENT COLOURS.
EVERY DIFFERENT COLOUR OF
LIGHT HAS A CORRESPONDING WAVE
LENGTH DEPENDING ON THE
PARTICULAR WAVE LENGTH AND
DEPENDING ON THE PARTICULAR
THICKNESS OF FILM, A DIFFERENT
COLOUR WILL BE REINFORCED.
IT'S AS IF WE'VE GOT
RINGS ON THE BUBBLE.
THESE ARE CALLED
NEWTON'S RINGS.
AND, IN FACT, THERE ARE MANY
CHARTS, WHICH YOU CAN REFER TO,
TO TELL YOU EXACTLY WHAT
THICKNESS A PARTICULAR
FILM WOULD BE.
THIS BECOMES VERY USEFUL WHEN
WE'RE LOOKING AT THINGS LIKE
THE WINGS OF A FLY.
IT'S ALSO GOT
THESE SAME COLOURS.
WHAT WE'VE GOT HERE IS A
USEFUL TOOL FOR HELPING US
UNDERSTAND WHAT'S HAPPENING
IN SOMETHING LIKE OIL OR GAS
ON THE ROAD, OR
THE WING OF A FLY.
IN GENERAL, IT'S AN APPLICATION
OF THIN FILM INTERFERENCE.

A slate appears with the caption “For more information read: Professor Bubbles. Official Bubble Book by R. Faverty and J. Jama. Copyright.1989. New York. Greenleaf. Bubbles, Drops and Particles, by R. Clift, J.R Grace, M.E Weber. Copyright. 1978. Academic.”

Another caption reads “A production of TV Ontario. The Ontario Educational Communications Authority. 1989.”

Watch: Newton's Rings