Magnetic induction - the levitating bbq
At the Palais de la Decouverte in Paris, a 1kg aluminium plate is levitated above a large coil of wire that is being supplied with 800A of alternating current at 900Hz.
Note the flare of the globes on the lamp when he moves it into the magnetic field and the steam coming off the surface - it’s also humming with the frequency of the alternating current. If you have time I recommend watching the video - it is very entertaining.
Since the oxide of osmium is volatile (i.e. it evaporates) and you can smell it, osmium is seldom used for anything practical as a pure substance. However one characteristic of osmium is that it is a very dense, hard metal. For materials that need to be hard and resistant to wear, like old school pens and phonograph needles, osmium used to be used, alloyed with other metals. Like in the Osmiroid pen tip. (photo credit)
I turned around. It was an older human. He was paler than Marco, but other features were similar.
Marco had warned me to say nothing to his father but “yes” and “no.”
“No,” I said to Marco’s father.
“I’m Marco’s dad. Are you a friend of his?”
“What’s your name?”
“No,” I answered.
“Your name is ‘No’?”
“That’s an unusual name, isn’t it?”
“Yes, it’s not an unusual name?”
“Now I’m totally confused.”
Marco’s father stared at me. Then, in a loud voice he yelled, “Hey, Marco? Marco? Would you… um… your friend is here. Your friend ‘No’ is here.”
“No,” I said.
“Yes, that’s what I said.”
Marco came running down the stairs. “Whoa!” he cried. “Um, Dad! You met my friend?”
“No?” Marco’s father said.
“What?” Marco asked.
Marco’s father shook his head. “I must be getting old. I don’t understand you kids.”
“Yes,” I offered.