Ever notice how cereal clumps up in your bowl, or how cereal sticks to the edges of the bowl? Bubbles in beverages do the same thing.You’ve probably seen this surface tension and buoyancy at work, but did you know there’s some mind-blowing science behind it? What we learn in our cereal bowl even connects to the lives of tiny insects that walk on water. Continue reading
Physics Girl astrophysics series – Brown Dwarfs are among the most recently observed objects in the universe. They have at MOST 8% the mass of the Sun. The lower mass boundary is not known! So they are halfway between stars and gas giant planets. Astrophysicist Daniella Bardalez Gagliuffi sits down with Dianna Cowern to discuss the latest research and the history of Brown Dwarfs Continue reading
What if you thought the earth was flat? And then you found out it isn’t? Continue reading
As of 1989, mankind had successfully sent craft to every known planet in the solar system except one: Pluto. Located in an mysterious region called the Kuiper Belt, Pluto is a scientific goldmine, and could hold clues to the formation of our solar system. Alan Stern explains how NASA’s New Horizons mission is going to allow us to see Pluto for the first time. Lesson by Alan Stern, animation by Eoin Duffy. Continue reading
The traditional incandescent bulbs used for teaching series and parallel circuits are rated for 3 V or 6 V. The problem is that many power supplies can generate higher voltages. As a result, it is common to have many blown bulbs. With several sections teaching this unit, bulbs can quickly become in short supply. Bulb replacements can cost $1.00 each, and often are included in the general department order at the end of each semester.
LED as an alternative: LED lights are rated for low voltages (3 V). However, by adding a small resistor (390 ohms) to one of the legs, the LED can be used at excessive electric potentials. After adding the resistor, the LED was successfully used at 13.88 V, the maximum value for my power supply.
Construction: The resistor and LED wire were twisted together. To be consistent, the resistor wire was attached to the anode (+) leg of the LED. To identify this, the LED was held up to a light. The smallest metal in the LED bulb is the anode (+). Solder paste was added to the two twisted wires. Using a pencil style soldering gun, the smallest drop of solder was added on to the soldering iron tip. The tip touched the paste and they were instantly soldered. Start to finish the whole process took less than a minute.
The advantages: The LED’s now can function at higher voltages, the legs can easily fit into breadboards or can be alligator clipped into circuits, and they are cheap. A kit with 100 LEDS, and 390 ohm resistors costs less than $12.00 from Qkit Electronics, Kingston Ontario.
This was initially presented at OAPT 2018 at Western University, London Ontario.
STAO Safety Chair
On Nov. 30, 2010, astronomers discovered asteroid 2010 WC9. However, it soon faded from view and was lost. But now it’s back, and it’s going to whiz past Earth Monday night. Continue reading
Throughout Earth’s history, climate has varied greatly. For hundreds of millions of years, the planet had no polar ice caps. Without this ice, the sea level was 70 meters higher. At the other extreme, about 700 million years ago, Earth became almost entirely covered in ice, during an event known as “Snowball Earth.” Continue reading
Mysteriously play an organ pipe without an organ! This demonstration uses heated air to produce vibrations inside a long tube. The vibrations, in turn, produce standing sound waves with a unique tone, or timbre (ta˘mʹ br)—the same concept that produces sound from an organ pipe.
The open tubes in this demonstration act in a similar manner to the flue-type organ pipe (see Figure 5). In a flue-type organ pipe, a stream of air is directed against a sharp edge in an opening of the pipe. The sharp edge creates turbulent, complicated swirls of air which set up vibrations in the air column.
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