Laugh out loud newbie question: how much does voltage matter

[Dubious Drewski]

So I just recently learned what voltage and amps were, but I'm wondering about something.

If amps are the actual measurement of electrical flow, then why are volts important? Voltage is a measure of the electrical "pressure", right? So as long as there are enough volts to get the electricity through the circuit, then why would you need more than the bare minimum?

In other words: if the electricity isn't going to be jumping across any gaps(not part of a normal circuit, I would hope), then why does voltage even matter if the true power comes from the amount of amps?

Feel free to laugh now.

EDIT: and one more thing: how can you have tons of Volts but very little amps? If there's tons of "pressure" I would think that there would be tons of "backed-up" electricity causing that pressure, which intuitively to me means, high amperage. I'm wrong obviously, but how?

 

[halls]

Re: Laugh out loud newbie question: how much does voltage ma

In other words: if the electricity isn't going to be jumping across any gaps(not part of a normal circuit, I would hope), then why does voltage even matter if the true power comes from the amount of amps?

Well this is a bit how car motors work. Car motors do have a power level. A motor power comes determined by P = F.v, where P is the power, F is the supplied force, and v is the reached velocity.
If you have a motor with a certain maximum amount of power, you will have to sacrifice some velocity as long as what you need is force, and same for force if you want velocity.
What I mean is, imagine you are climbing a very steep slope. Your motor will need much force to move all your car's weight, so you will be moving slow... But if you are in the middle of the highway, you might be driving at 100 km/h, so the force your motor will be supplying won't be very high.

It happens very similar in electronics. A power supply may give a maximum amount of power, which is P = V.I (actually this is much more complex than this, but just to get an idea). Your circuit may be needing very high voltage to work, so the supply won't be giving much current flow (this is the typical scene), but you might encounter some circuit with a very low need of voltage but a very high need of current flow.

You have to imagine the voltage as the "strength" needed to move electrons, and the current as the amount of them moving. For example in a silicon diode you need 0.7 volts to get the electrons trespassing a voltage barrier, but that's independent of how many of them you want trespassing. So you might be giving 0.7 volts to the diode so the electrons can go through the barrier, but that might not move enough electrons for your circuit, so you just have to supply more volts so you get the current flow needed AND that barrier trespassed.

I'm sorry if i write too much, just trying to get this clear...

EDIT: and one more thing: how can you have tons of Volts but very little amps? If there's tons of "pressure" I would think that there would be tons of "backed-up" electricity causing that pressure, which intuitively to me means, high amperage. I'm wrong obviously, but how?

this one is easy: Imagine a water pipe, with lots of water pressure, and thus, lots of water flow going through that pipe. After going through the pipe, the water finds another pipe at the end of the first one, which has a smaller width. Do you think the water flow will be the same? I mean, do you think that the same amount of water will be going through both pipes? Obviously not, but they still have the same water pressure.

This is the analogy with volts and amps. Amps are the current flow, and volts the pressure. If the electrons find some resistance to the current flow, there will be less current flow, but the voltage will remain the same.

This is known as Ohm's law, which says that V = I.R, where V are volts, I are amps, and R are ohms, this is, electrical resistance.

You can have a 1 megavolts source, but as long as you have 1 gigaohms resistance there will be just 1 milliamperes of current flow.


Again sorry for this much text, but i just want to get this clear

And don't be afraid of asking, nobody's going to laugh, we all had have to learn from the beginning

 

[BeeBop]

Re: Laugh out loud newbie question: how much does voltage ma

Halls, you are correct, right up to the point you say this:
[/quote]
this one is easy: Imagine a water pipe, with lots of water pressure, and thus, lots of water flow going through that pipe. After going through the pipe, the water finds another pipe at the end of the first one, which has a smaller width. Do you think the water flow will be the same? I mean, do you think that the same amount of water will be going through both pipes? Obviously not, but they still have the same water pressure.
[/quote]
In this case, the velocity of the water will increase, and the pressure will decrease. The same amount of water will flow. To see this at work, slightly pinch a garden hose, and you will see the velocity increase. This is the principal on which the venturi in a carburetor works.

 

[halls]

Re: Laugh out loud newbie question: how much does voltage ma

well maybe that wasn't the best example (i'm not really good at thermodynamics) but what i meant is that a lesser amount of water will flow per section.

Look, current flow is I = dq/dt (where q is the charge) which means that the variation in charge will give the current flow.

The electrical resistance is the resistance the electrons find to their flow, this is, when flowing through a conductor they might find some atoms that slow their flow (because they collide with them, for example). When flowing through a cable for example, the thinner the cable, the larger the resistance (less space for atoms to flow). This is, the higher the resistance, the lesser electrons will be flowing, or the ones that are already flowing, will go slower (colliding with atoms once a while)

not sure if this clears it a little bit... doing my best

 

[ehsanelahimirza]

voltage is very important in each aspect

i will give u the example for tranmission lines of very high voltages

power P=VI
why we raise V and decrease I keeping P same

its beacuse of resistance of wires and power loss in them that is I^2*R
some voltage will be dropped, if 100 volts are dropped from 11000KV that doesnt matter.

then we have almost the same power at the end
that is now DUE TO THE HIGH VOLTAGE

 

[rkodaira]

Re: Laugh out loud newbie question: how much does voltage ma

Dubious,

As your name indicates, and you are learning about electricity and electronics, learn the right way: try to use the correct names and abreviatures for the physical units.
Do not use "amps" for electrical current unit as it can be confused with "amplifier" abreviation (most use the term Op Amps for operational amplifiers). I got confused with your DUBIOUS statement.
Use "amperes" and A, use "volts" and V, use "watts" and W, use "ohms" and Ω, use "farads" and F, use "henries" and H.

 

[Awarapunshee]

Re: Laugh out loud newbie question: how much does voltage ma

The Voltage is actually potential difference. Unless you have and potential difference at both end of a conductor, you won't have current to flow. For example if at one end you have 5V and other end at 0V (w.r.t some common point), there will be a flow of current between the two points (according to ohm law V=IR). But if you have both end at 5V (w.r.t some common point), no current will flow. And also the make the difference more with the same conductor more current will flow.
I hope this will give concept of voltage and current.

Regards

 

[Khabree]

Re: Laugh out loud newbie question: how much does voltage ma

Dubious Drewski

I will give you an example for understanding of voltage and current. If there is two water tank, connected with a pipe at the base of both tank and equal amount of water. if both have at the same height with respect to earth, then no water will flow through the pipe, but if you raise one tank, there will be created a height difference and water will flow, higher the difference in height, more water will flow.
So here water pipe is a conductor, tanks are sources and height is potential. so higher the potential difference, more current will flow.

 

[nikhilele]

there are two types of devices..
current driven
and
voltage driven...

can some body explain that... and give some examples

 

[yeechyan]

Re: Laugh out loud newbie question: how much does voltage ma

BJT is current driven device. It needs a current supplied to it's base terminal in order to turn it on.

MOS is voltage driven device. It needs a voltage across the gate to source terminal in order to turn it on.

 

[miGs]

Re: Laugh out loud newbie question: how much does voltage ma

If amps are the actual measurement of electrical flow, then why are volts important? Voltage is a measure of the electrical "pressure", right? So as long as there are enough volts to get the electricity through the circuit, then why would you need more than the bare minimum?

You need "more" than the bare minimum to pass the "circuit" so as to feed your loads, such as appliances from the wall outlet. The wires or conductors of the circuit has "voltage drop" (this is the bare minimum to pass the circuit), so if you will have a voltage just enough for the voltage drop, nothing will be left for your load.

In other words: if the electricity isn't going to be jumping across any gaps(not part of a normal circuit, I would hope), then why does voltage even matter if the true power comes from the amount of amps?

Power is also a function of voltage and not just current. P = VI. So how much power you will have depends also to the voltage you have.

EDIT: and one more thing: how can you have tons of Volts but very little amps? If there's tons of "pressure" I would think that there would be tons of "backed-up" electricity causing that pressure, which intuitively to me means, high amperage. I'm wrong obviously, but how?

I think you are referring to the case of transmission lines, where the voltage are of the hundred kilo-volts level. Please note that the little amount of current is due to the transformers used to step-up the voltage. When using transformer, the higher the voltage the lower the current (this is where AC beats DC).
You might ask why? This is to compensate for the voltage drop (as you know transmission lines are miles apart), and maintain the desired voltage level at the receiving end. Economics is of prime consideration as to the size of the conductors (cost is proportional to the size), support or towers etc.