# a query regarding current and voltage.

Discussion in 'General Electronics Chat' started by jeyshree07, Jan 5, 2011.

1. ### jeyshree07 Thread Starter New Member

Jan 5, 2011
2
0
Hello,
Will someone please explain me whether my understanding about voltage, potential difference and current are correct?
According to me,
Voltage is like the food we eat , which is a chief source of energy. similarly in a conductor free electrons move randomly in all possible directions. so in order to make the electron move in one direction we need to supply an energy .that is nothing but voltage.
Potential difference:

Consider a man standing at point a he possess 500calories of energy.when he walks for 5m and reaches position b he possess 480 calories of energy.so he lost 20 calories of energy that is the potential difference.
It is applicable for electron too

When an electron is at position a it possess 5v of energy(potential).when it moves and reaches b it possess 3v of energy(potential).thus the energy lost (5-3)v=2 volt ,is the potential difference.
Current:

It is the number of electrons crossing position a at a unit time.
If I were wrong please correct me.

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
282
Speaking for myself, I find that the analogies always break down at some point and become a hindrance.

Voltage is a difference in electrical potential between two points. The potential may be created chemically or mechanically.

If a conducting path is made between those points, the potential difference will cause electrons to move under the influence of the voltage difference. The current of electrons is regulated by the voltage (also electromotive force, if you like) and the resistance in the conduction path.

Simple as E = IR.

3. ### Len Whistler Member

Dec 10, 2010
44
3
I also don't like analogies, but here is one I just made up.

Lets say the weight of a car is "volts" and its speed is "current" (amps). The car hits an object at 2 mph and 40 mph. Both impacts have the same volts but it's the current (amps) that does the damage.

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4. ### JDT Well-Known Member

Feb 12, 2009
658
85
I always think water is a good analogy. Imagine a tank of water on a high tower. Imagine a pipe coming down from this tank to a valve at the bottom.

The higher the tank, the greater the pressure of the water at the valve. This is the voltage.

The current is the amount of water flowing. Valve closed, no flow - whatever the pressure. Open the valve slightly and water flows. With a high tank (high pressure) the water flows very fast - high current. Low tank (low pressure) and the valve open the same amount the flow will be much less - lower current.

The valve, of course, is a resistor.