pallavi agarwal
Member • Jun 21, 2008
Why is current so small in size?
why is current so small in size?
Howdy guest!
Dear guest, you must be logged-in to participate on CrazyEngineers. We would love to have you as a
member of our community. Consider creating an
account or login.
Replies
-
Administrator • Jun 21, 2008
Didn't get your question.pallavi agarwalwhy is current so small in size?
Probable answer could be: Because its made up of electrons. 😁Are you sure? This action cannot be undone. -
Member • Jun 21, 2008
Haha, he meant why current values are always in the milli range and such. I think..Are you sure? This action cannot be undone. -
Member • Jun 21, 2008
If current was any larger it wouldn't fit through the tiny wires...
ok, so that was a lame joke.
Can you explain your question a little bit more?Are you sure? This action cannot be undone. -
Member • Jun 21, 2008
Well, we have been thought current is some'thing'. Current is just flow of energy (not even electrons, they dont travel from one end to the other you know).
====offtopic===
Gohm:
1. I am very interested in what you said about discussing antique inventions and discoveries of Da Vinci and Wright bro's. I have a book on da vinci, and wow, he was a genius of his time.
2. I wish you could contribute on CEbot 😀Are you sure? This action cannot be undone. -
Member • Jun 22, 2008
Current Cur"rent, n. [Cf. F. courant. See Current, a. ]
[1913 Webster]
1. A flowing or passing; onward motion. Hence: A body of
fluid moving continuously in a certain direction; a
stream; esp., the swiftest part of it; as, a current of
water or of air; that which resembles a stream in motion;
as, a current of electricity.
[1913 Webster]
So my dear friend, you must first mention what you mean by current? (Even if, we may safely assume here that you're speaking of electric current).
Now speaking of electric current, thanks to nano watt technology, modern mico-electronics work with as little as a few nano Amps. But then look at the transmission cables and you'll find that some of them carry kilo Amps of current. So before commenting on size of current we must specify the circuit through which current is flowing.
The unit of current being Ampere is approximately equivalent to 6.24150948×1018 elementary charges, such as electrons, moving past a boundary in one second.Are you sure? This action cannot be undone. -
Member • Jun 22, 2008
Hey current ranges changes acording to application,transmission lines carry high-current and so on.......mostly in electronic we use low currentAre you sure? This action cannot be undone. -
Member • Jul 6, 2008
The question is not clear enough. And if he meant that usually Current is in mA range, he is wrong. Ok. current in electronics is in mA range. But when it comes to transmision , its in the range of 100 A and above depending on load. Thats why we use current Transformers. If all current was in mA range, then we wouldnt need CT'sAre you sure? This action cannot be undone. -
Member • Jul 6, 2008
xheavenlyxWell, we have been thought current is some'thing'. Current is just flow of energy (not even electrons, they dont travel from one end to the other you know).
It isn't? I thought that current flow was the passage of electrons from differing potentials. Wouldn't there be current flowing between the two ends of a chemical cell?Are you sure? This action cannot be undone. -
Administrator • Jul 6, 2008
@xheavenlyx - Hey, electrons DO travel, don't they?
That's what I've been taught!Are you sure? This action cannot be undone. -
Member • Jul 7, 2008
actually, even my teachers told me the same. But its like this: (sorry, I had an excellent link on Lies and Myths of Electrical Engineering, lost it or dont rem).
Yea so here is an explaination:
... [SIZE=-1]individual electrons do not continue through the conductor in straight line paths, but instead they move in a random zig-zag motion, changing directions as they collide with atoms in the conductor. (the speed of this random motion is called drift velocity)[/SIZE]
So electrons do travel BUT they dont "Circulate" the "Circuit"!
[SIZE=-1] For example, the drift speed through a copper wire of cross-sectional area 3.00 x 10-6 m2, with a current of 10 A will be approximately 2.5 x 10-4 m/s or about a quarter of a milimeter per second. [/SIZE]
[SIZE=-1]
Thats slower than your car! i.e: 30 km/hr is 8333.33 mm/sec!
So how does it travel SO fast?
[/SIZE][SIZE=-1]
Information from [SIZE=-1]Matt G., Engineering Student, University of Texas at Austin and Anton Skorucak, PhysLink.com Editor[/SIZE]
So how does an electrical device turn on near instantaneously? If you think of a copper wire as a pipe completely filled with water, then forcing a drop of water in one end will result in a drop at the other end being pushed out very quickly. This is analogous to initiating an electric field in a conductor.[/SIZE]
But still try not to use the water analogy (a lot) with electric current as they are very different. Thats the reason for kritchoffs voltage and current law being a bit difficult. (It was hell for me even though I loved the subject...my basics were shrewd up)
[SIZE=-1][/SIZE]Are you sure? This action cannot be undone. -
Member • Aug 30, 2010
What she meant to ask is "Why is the value of current less in numerical size than voltage?" That is a question even I have felt some time ago. See, we cannot afford to bring the voltage and current into something looking numerically equal in size. Power can be given by the equation-pallavi agarwalwhy is current so small in size?
P=VI (Power=voltage*current)
so, it is clearly a product of current and voltage. We can have any value of current and voltage from a power source. But we have to take into consideration the problems if we take any value for V or I. The problem with taking high value of current is explained here
>In every wire, current flow causes heating up of the wire(heat dissipation). The heating up is a loss, known as heat loss, which is dependent on the square of the current. Thus, if we have a very high value of current, we will have higher losses. Thus, inefficient transmission(transmission with losses) happens. We don't want to transmit power with high losses, do we? So that is the reason why we keep the value of current low and bring the value of the voltage to a bigger value.
Hope I answered you to your satisfaction.Are you sure? This action cannot be undone. -
Member • Aug 31, 2010
First thing you cant compare VOLTAGE with CURRENT as they are two different things.........aj_ondutyWhat she meant to ask is "Why is the value of current less in numerical size than voltage?" That is a question even I have felt some time ago. See, we cannot afford to bring the voltage and current into something looking numerically equal in size. Power can be given by the equation-
P=VI (Power=voltage*current)
so, it is clearly a product of current and voltage. We can have any value of current and voltage from a power source. But we have to take into consideration the problems if we take any value for V or I. The problem with taking high value of current is explained here
>In every wire, current flow causes heating up of the wire(heat dissipation). The heating up is a loss, known as heat loss, which is dependent on the square of the current. Thus, if we have a very high value of current, we will have higher losses. Thus, inefficient transmission(transmission with losses) happens. We don't want to transmit power with high losses, do we? So that is the reason why we keep the value of current low and bring the value of the voltage to a bigger value.
Hope I answered you to your satisfaction.
Second Thing If you want say that current is always in small in number than voltage, current is totally depend on resistance of Line or Wire......
Resistance decides the magnitude of current...... As, I = (V/R).........Are you sure? This action cannot be undone. -
Member • Aug 31, 2010
The reply I have given is in a broad sense. See, the resistance level of appliances or equipments are decided by us. If we want, we can decrease the resistance of the appliances. Now when we do that, the current value will increase. To accommodate such a large current, all we need are larger conductors. Now larger conductors mean more production cost. To minimise the production cost, we have to bring down the current value. That is why we increase the resistance of the equipments. Keep it in mind that in most cases, the its the power supply that designs the apparatus, the apparatus doesn't design the supply.d_vipulFirst thing you cant compare VOLTAGE with CURRENT as they are two different things.........
Second Thing If you want say that current is always in small in number than voltage, current is totally depend on resistance of Line or Wire......
Resistance decides the magnitude of current...... As, I = (V/R).........Are you sure? This action cannot be undone. -
Member • Sep 1, 2010
I agree with most of the comments regarding current. It is indeed flow of energy but it is the electron flow that makes up this energy and it is electrically speaking. There are several forms of flow of energy in the discussion's case it is electrons.
Please anyone knows about Leaky cables leave me a message please. Thanks.Are you sure? This action cannot be undone. -
Member • Sep 1, 2010
Kindly view the thread dealing with leaky cables, search for it., there is a mention of it in the thread #-Link-Snipped-#, and there is a thread devoted for leaky cables, if my memory is correct.euieLCPlease anyone knows about Leaky cables leave me a message please. Thanks.
Thank you.Are you sure? This action cannot be undone.