Build an intuitive understanding of current and voltage, and power.
Log in Lynch.Steven 8 years agoPosted 8 years ago. Direct link to Lynch.Steven's post “I still don't get Amperes...” I still don't get Amperes, can someone please help with a simple analogy so I can understand better? • (84 votes) auden 8 years agoPosted 8 years ago. Direct link to auden's post “Think of a tank of water ...” Think of a tank of water with a hole in it. The amount of water in the tank is the voltage, aka the potential/volts. The size of the hole is the resistance, aka the ohms. The amount of water that flows would be the amps in this example. If you wanted to add watts into this system, say you put a water wheel in that stream of water. The power produced would be watts. (100 votes) Ruchit patel 8 years agoPosted 8 years ago. Direct link to Ruchit patel's post “what is quantum mechanics...” what is quantum mechanics ? please explain in brief • (14 votes) balzamondrafe13 8 years agoPosted 8 years ago. Direct link to balzamondrafe13's post “a body of principles that...” a body of principles that explains the behaviour of matter and it's interactions with energy on the scale of atoms and subatomic particles (58 votes) Eric George 7 years agoPosted 7 years ago. Direct link to Eric George's post “If water is a poor conduc...” If water is a poor conductor of electricity, why do we get electrocuted if we stand in water and electricity is introduced? • (7 votes) V_Keyd 7 years agoPosted 7 years ago. Direct link to V_Keyd's post “Pure water is poor conduc...” Pure water is poor conductor of electricity but the water in your tap contains many minerals that provide the ions for conduction of electricity. Similarly if you take pure water and dissolve a teaspoon of table salt (NaCl), it would become a good conductor because now it would have sodium and chlorine ions to help conduct electricity. Do note that at very high voltages, even pure water starts to conduct electricity because water molecules become ionized and separate into H+ and OH- ions which results in increased conductivity. (37 votes) Arulx Z 8 years agoPosted 8 years ago. Direct link to Arulx Z's post “Can someone elaborate the...” Can someone elaborate the formula dU/dt • (12 votes) Barry Kinnan 8 years agoPosted 8 years ago. Direct link to Barry Kinnan's post “I posted in tips if you a...” I posted in tips if you are not familiar with derivatives. (3 votes) Pragatheeswaran 8 years agoPosted 8 years ago. Direct link to Pragatheeswaran's post “The electric power consum...” The electric power consumed by a device may be calculated by using either of the two expressions P=I^2 R or P=V^2 /R. The first expression indicates that it is directly proportional to R whereas the second expression indicates inverse proportionality I Know, if you have a constant voltage, increasing the resistance decreases the current flowing in the system by Ohm's law and hence decreases the power consumption However, if you have a constant current source, increasing the resistance increases the voltage dropped across the resistor and hence increases the power consumption. But more intuitively I wanna know about this, with some example....can anyone please explain me? Thanks is advance • (2 votes) APDahlen 8 years agoPosted 8 years ago. Direct link to APDahlen's post “Hello Leo,CAUTION - thi...” Hello Leo, CAUTION - this is an answer from an electrical engineer... In my opinion the voltage source is relatively straightforward. Examples include a battery or wall outlet. As you stated as the resistance is decreased more current flows. With more current and a fixed voltage there will be more power. The current source is a different animal. I'll give you a few examples to consider: 1) The current source is a mathematical construct that maintains a constant current. It will take on whatever voltage is necessary to do so including both positive and negative voltages. It has an infinite impedance. To my knowledge there are no perfect constant current sources. To make one you would need a device that could produce an infinite voltage (not possible). 2) Please search "Thevenin Norton Equivalent." Here you will find that a voltage source with series resistance can be modeled as a current source with parallel resistor. Note that there is no such thing as a perfect constant voltage source. Such a device would demand infinite current (again, not possible in this universe). 3) Please search "inductor kickback." Here you will find than an inductor acts as a constant current source for a limited amount of time. As the inductor is "turned off" it will act as a constant current source and do whatever is necessary to maintain the same current before and after the transition. 4) Please search "transistor characteristic curves." Here you will find that a transistor appears to operate as an acceptable constant current source. I hope you like these examples. Know that it will take some time for the material to sink in. May I recommend you print this note and check things off as you have master the topics. Please leave a comment below if you have any questions. Regards, APD (12 votes) Charlie Brooks a year agoPosted a year ago. Direct link to Charlie Brooks's post “This is more of a "dumb c...” This is more of a "dumb curiosity" question and is purely hypothetical, but if salt water is as good as copper and silver could it be used to help power most things we use today? • (2 votes) Willy McAllister a year agoPosted a year ago. Direct link to Willy McAllister's post “Good day dream question. ...” Good day dream question. Salt water happens to be NOT as conductive as copper and silver. Those two metals are very good conductors compared to sea water. Sea water has a conductivity of 5 x 10^6 S/m But suppose these numbers were closer. Water is a lot cheaper than copper, so that's an advantage for water. Now all you have to do is figure out how to use the water to build the electronic gizmos we all love. That's where water becomes distinctly useless as an electrical interconnect. Can you imagine if all the phone lines and power lines you see going from pole to pole were garden hoses? (12 votes) DC83 7 years agoPosted 7 years ago. Direct link to DC83's post “In the analogy for voltag...” In the analogy for voltage, where you compare it to a ball rolling down a hill, does voltage increase as it rolls down the hill, i.e. does it build momentum with gravity? • (5 votes) Teacher Mackenzie (UK) 7 years agoPosted 7 years ago. Direct link to Teacher Mackenzie (UK)'s post “nice question:OK, so th...” nice question: OK, so think about potential. : it means stored energy or energy capable of doing work... So think about the ball, at which point does it have most potential energy? top of hill or bottom?? OK? (5 votes) ANI 7 years agoPosted 7 years ago. Direct link to ANI's post “Why is I the symbol for c...” Why is I the symbol for current? • (3 votes) Salman Sheikh 7 years agoPosted 7 years ago. Direct link to Salman Sheikh's post “intensité de courant, (cu...” intensité de courant, (current intensity) in French. It was used by André-Marie Ampère. You can guess who that guy was. That is why we use I as symbol for current (8 votes) Jane He 8 years agoPosted 8 years ago. Direct link to Jane He's post “what's the difference bet...” what's the difference between charges and electron/proton? since in my mind, current is caused by the moving of electron, but the text says that charges cause it. • (3 votes) Andrew M 8 years agoPosted 8 years ago. Direct link to Andrew M's post “Current is the movement o...” Current is the movement of charge. Since electrons are particles with negative charge, their movement creates current. (6 votes) Jack Kovski 7 years agoPosted 7 years ago. Direct link to Jack Kovski's post “Is there a reason why pro...” Is there a reason why proton's charge is called positive and electron's charge is called negative? • (3 votes) Willy McAllister 7 years agoPosted 7 years ago. Direct link to Willy McAllister's post “A long time ago, Ben Fran...” A long time ago, Ben Franklin (the American statesman) proposed a theory of electricity where he thought electricity was a fluid. This was back when the only thing anyone knew about electricity were those static electricity experiments you can do with a comb through your hair or rubbing a balloon on your sweater. Nobody knew about atoms or electrons or protons. Anyway, Franklin proposed an object could have extra electric fluid or lack fluid, depending on what you rubbed it with, and that's what caused the static attraction, the different levels of electric fluid in two materials. He called the "lacking" material negative, and the extra material "positive". About 150 years later the electron was discovered, and it turned out that the "lacking" materials actually had an excess of electrons. And that's how the electron got its negative sign. (6 votes)Want to join the conversation?
Copper has a conductivity of 6 x 10^7 S/m, or 10 times higher.
