Dick groaned in annoyance as he glared at his homework.
"What's up?" The blonde haired Artemis asked as she sat next to the boy.
"I'm having problems with my physics homework." The thirteen-year-old boy groaned again and let his head hit the table.
"Can't help ya there…Hey Wally!" She yelled loudly.
"S'up?" The young speedster asked.
"He needs help," Artemis gestured to the raven haired boy, "with physics."
"When did you get here?" Asked Dick as he sat up. The red head boy gave his friend a look.
"Okay you must be stressed. I've been here for an hour. What do you need help with?"
"Everything." Wally nodded and sat on the other side of the teen.
"Well let's start out on the first question."
"What's the difference between electrical potential energy and electric potential?"
"Okay so let's start off with the first part of the question, electric potential energy. Energy an object has due to it's location is called potential energy right?" Dick nodded, "So a charged object can have electric potential energy depending on its location on an electrical field. Do you understand that part?"
"Yeah." Was Dick's response.
"No." came from Artemis. Wally waved the blonde off.
"Okay now electrical potential. Electrical potential is the Voltage. Do you know what the voltage is?"
"It's a ratio…right?" Dick asked uncertain. Wally nodded.
"Yeah, can you tell me what the ratio is?"
"Err…" Dick looked over his notes before he answered, "Change in electrical potential energy over the amount of charges moved?" Dick looked at his friend for conformation. With a grin Wally nodded.
"Okay I understand this now."
"I don't." Artemis spoke up.
"Good thing I'm not helping you then, okay number two: What is the SI unit to measure electrical P.E?"
"It's measured in Joules."
"Correct, number three: What is the SI unit t measure electrical potential." Dick bit his lip as he thought about it, trying not to look at the notes.
"Remember that's just a fancy way to say Voltage."
"…It would be…volts, joules over coulombs."
"See you're getting it!" Wally patted Dick's back then went back to the problems, "How can electric potential be high when electrical potential energy is relatively low?" Dick thought for a moment with furrowed brows. With narrowed eyes he began.
"Voltage is a ratio while the e.p.e is only a single number…ratios can be higher than a single number amount."
"A bit wordy but yeah. What will happen to the electrical potential energy of a charged particle in an electric field when a particle is released and free to move."
"Released to move around…that would make it kinetic energy right?" Artemis questioned the two boys. Dick nodded.
"Yeah it would, so that would mean the potential energy would go down."
"Ding, ding. Question 6: Define volt in terms of the change in potential energy of a charge moving in an electric field." Wally was met with two blank looks. With a dramatic sigh Wally started explaining.
"It goes back to voltage being change in electric p.e over amount of charge moved. So when we are talking about volts the variable for the p.e is w, which stands for work. Energy is the ability to do work okay?" that earned nods, " so can you tell me what the variable for the amount of charge is?"
" It's q' right? Oh so the answer to the question would be V= w/q'." Dick asked.
"There you go! See sometimes you just over think things."
"If 120.0 J of work are performed to move one coulomb of charge from a positive plate to a negative plate, what potential difference exists between the plates?" Artemis read allowed.
"So what equation would you use?" Wally asked his younger friend.
"Voltage= w/q', since it says work."
"Right, so what other variable do you have and what are you trying to find?"
"One Coulomb…so I have q' and I'm looking for the voltage. w= 120 and q'= 1. V= 120/1 so the voltage is 120 J/C."
"How much work is done to transfer 0.15 C of charge through an electric potential difference of 9.0 V?"
"So let's see if V= w/q' and I'm solving for w then I'd multiply V with q', so vq'=w. V= 9.0 J/C and q'=.15 C… 9.0*.15…so w= 1.35 J. Then round it so the answer is w = 1.4 J."
"Why are we helping a math nerd again?" Artemis question Wally. Wally gave her a funny look.
"Uh no offence but you aren't really helping, you could leave if you wan to."
"He has a point, you just won't because no one else is around. I'm not saying I want you to leave," Dick quickly said as Artemis glared, "I like hanging out with you guys, I was just pointing out the facts."
"Well hurry up, there's four more problems then we can go do something like, I don't know, prank people." Artemis suggested. Wally and Dick grinned and they started right back in to the work.
"Have to get Barbra back for that last prank." Dick muttered as Wally read aloud the next problem.
"An electron, which has a charge= -1.6 X e-19, is moved through an electric potential difference of 500. Volts. How much work is done on the electron."
"Looking for w again, so it's vq'= w again… Let's see 500* -1.6 X e-19…so that would mean w= 8.0 X e-17 J."
" A 12 V battery does 1200 J of work transferring charge. How much charge is transferred?" Wally asked.
"So now I'm finding q'… so q'= w/v…let's see 1200/12 so then q'= 100 C."
"Don't forget that because it's a single and not a ratio that you should change it to scientific method, so it would be 1.00 X e2 C."
"A voltmeter indicates that the electric potential difference between two plates is 50.0 Volts. The plates are 0.020-m apart. What electric field intensity exists between them? Okay so this won't be the same equation." Dick studied his notes then looked over the equation again.
"It would be V= Ed, d being the distance."
"What's E?" Artemis questioned.
"…the energy?" Wally nodded beaming, "Since I'm solving for e then v/d= e. 50.0/ .020 and that would be…
"What measurements are you using now?" Wally interrupted.
"Newtons and meters. Newtons are for force and meters for distance." Wally nodded.
"I just wanted to make sure you knew what to use." Wally explained.
"50.0 V/ .020 m= 2,500 V/m."
"Remember though V= J/C and J= n/m."
"So it would be n/m over C times m making it n/c. Then that would mean e= 2,500 n/c."
"Last one, the potential difference between a storm cloud and the ground is 5.0 X e7 volts. During a lightning flash, 3.0 coulombs of charge is transferred to the ground. How much energy is transferred to the ground in this lightning flash?" Artemis spoke.
"Coulombs and volts, so I'm finding work again?" Dick looked over to Wally to make sure. Wally nodded and Dick went back to the problem.
"Hmm… Vq'= w… (5.0 X e7) X 3.0= w. Then w= 150,000,000 so then the answer is w= 1.5 X e8 J." Wally grinned largely and wrapped an arm around his shorter friend's shoulders.
"There you go buddy! Now what did you say about pranks?" Wally asked Artemis as both boys looked to her with a gleam in their eyes.
