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BABATUNDE OGUNLADE: Hello, everyone. Today we're going to be working through Goodie Bag 5, which is on electronic materials, namely semiconductors. In order to follow along, you'll need a multimeter, a pair of alligator clips, some large LEDs-- I'll be using red, white, blue, and green-- and some regular sized LEDs. I'll be using red, blue, and purple. Our main objectives today are to identify differently colored LEDs by irradiating them with light across the visible light spectrum. And in the process, to explore the relationship between the bandgap of a semiconductor and its critical absorption wavelength. As we work through the Goodie Bag, I'd like you to think about how the size of the bandgap of material may influence which wavelengths of light you can absorb. Let's get started. First, connect your black or negative lead to the 10 amp port on the multimeter, and then your red or positive lead to the voltage ohm milliamp port. Then connect the p...

BABATUNDE OGUNLADE: Hello, everyone. Today we'll be working through Goodie Bag 3, which is on ionic solids. In order to work through this Goodie Bag, you'll need a conductivity meter, some small measuring cups, some medium sized cups, a small scale, a writing utensil, some nitrile gloves, some stirrers, and four unique solids. Today, I'll be using sodium chloride, magnesium sulfate, magnesium oxide, and sucrose. Our main objective today is to use solubility and conductivity measurements to determine if a given solid is an ionic or covalent compound. And as we do this, I'd like you to think about two questions. First, how do solids dissolve in water? And second, what factors may influence how conductive a given solid is in water? So first we're going to look at the solubility of our solids in water. And to do this, we're going to dissolve 1 gram of each solid in 30 milliliters of water. I've already weighed out my solids here. And I've also ...