Harry Potter: Where's the Juice?
"Lemons!" Ron shouted when he walked into the classroom. "Why are there lemons everywhere?"
Mr. Johnson smiled at Ron's enthusiasm. "Today we'll be doing experiments with electrolytes and electrodes to make a chemical cell."
Ron's enthusiasm was quickly replaced with confusion. "Huh?"
"Do you not know what any of those are? Well, guess I must fill you in before we start. Sit down, class. We're having a small lecture before we begin. So, electric current is the rate at which charges pass against a given point. It's basically what runs through wires when electricity is created. But, to create a chemical cell, you need some things. You need an electrolyte, which allow charges to flow, and two electrodes, which is the part of the cell through which charges enter and exit. Normal electrodes are made of metals because they are good conductors, which means they have less resistance and let the charges flow. It is the opposite of an insulator, which have high resistance, and charges do not flow. Oh, I forgot one important piece of information. Voltage is the electron moving force in electricity. It's how we measure the electricity and all that. That's what we will be measuring today. Any questions?"
Seamus raised his hand. "What's this got to do with lemons?"
His question was ignored. "Now, I think this is a particularly fun experiment. We'll be taking the metal electrodes and sticking them into the lemons to see which combination will produce the highest voltage. There are specific instructions at your lab table which you must follow. Begin."
There wasn't as much hesitation as previous times to get to the lab stations. Lemons seemed exciting, although Harry was a little worried about getting lemon juice in his eye. Or his nose – he'd had a bad experience with that in the past.
"So what do we do first?" Ron asked. "I can't decide which one would be more fun to stick in a lemon."
Hermione rolled her eyes. "Ron, we have to tackle this logically. We have to think of how many possible combinations there are and take it one by one."
"You always suck the little bit of fun out of science."
"Science is fun! Anyway, there are eight combinations. Let's start with this one." She picked up two strips of zinc and stuck them, precisely, into the lemon. She hooked the clips up to the strips of zinc and looked at the reading on the magical machine they were attached to.
"WOAH! What is that?" Ron asked, pointing to the magical machine.
"It's a voltage probe. It tells us the voltage of the lemon and electrodes."
Ron was staring at the machine, bug-eyed. "Cool," he whispered. Hermione was moving on to the next combination, and Harry was attempting to help.
"Erm…the others aren't going to cause any havoc with the lemon juice, are they?" he asked cautiously.
"Most likely not," Hermione said. "Why do you ask?"
Harry flicked his eyes over toward the adjacent station. "Um…"
And, as expected, there was a BOOM, and the station exploded. Except, it wasn't chunks of debris that came flying at them – it was a lighter spray of yellow this time, and it stung when it hit Harry's eyes. The lemon juice stung the eyes of everyone, and they started crying out in pain.
"Ow!"
"My eyes!"
"I hate lemons!"
"SEAMUS!"
Seamus was the only one not cowering in pain, having avoiding the blast. He grinned at his excellence. Harry, however, was covering his eyes and writhing on the floor. The bad memories were coming back to him. No. No. Not the lemons…
He was among the people who were running out of the classroom even before Mr. Johnson, also a victim, shouted "Class dismissed!"