In wires the current is always carried by electrons. Even with wires we still use conventional current direction to indicate the flow of positive current. The electrons are still moving in the direction they are supposed to, which is in the opposite direction of the current arrow. The instrument we use to measure current—an ammeter—cannot tell the difference between positive charge moving one way from negative charge moving the other way.
An ammeter reports a single number when it measures current. It displays one number for the combined amount of positive and negative charge moving around see the definition of current.
An ammeter displays a positive sign when current the direction positive charge would flow flows in the red lead and out the black lead. The current arrow points in the direction electrons are coming from. The blue arrows indicate the conventional current direction in both cases.
The meter reads a positive current. The meter reads a negative current. Electrons flow in the opposite direction of the blue arrows in both cases. Some military electronic training programs for example the U. If you participated in electronics training in the military you may have come across this convention. We follow the SI convention for current direction, which is defined in terms of positive charge. The conventional direction for maps is North at the top. Another convention is how sailors identify the direction of the wind.
A West wind blows from the west, toward the east. A west wind means we will have lunch farther east from here. Time for me to paint something. How did the electron get its negative sign? Franklin published a theory saying electricity was a single invisible fluid. His reasoned if you rubbed a glass rod with fur, one of them gained electric fluid and the other lost or lacked fluid. The electron was discovered years later and we finally understood the structure of the atom.
Lacking fluid meant it had excess electrons. Changing from Conventional Current to Electron Flow would cause a degree of confusion for old and new students and errors would occur, so Conventional Current was kept to ensure there was no confusion with those already trained with Conventional Current.
Two systems may seem confusing, but as long as usage is consistent, it really is not! You must realize what convention is being used because the rules change. Throughout this course, Conventional Current is used. If you open the switch, no current will flow anywhere in the circuit. It will not flow from one from one pole of the battery to the lamp. For simple circuits like yours, the current is identical at every point in the circuit.
Hence, inserting a resistor anywhere will reduce the current everywhere in the circuit. Whether you are looking at conventional current or real current negative electrons my first two points are always valid. Hence it does not matter what type of current you use. Note that with circuits that are more complicated and have multiple branches, the currents in the branches will not necessarily be the same.
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Create a free Team What is Teams? Learn more. Why is conventional current still used in schematic diagrams? Ask Question. Asked 3 years, 5 months ago. Active 2 months ago. Viewed 4k times. For example, take this circuit that was shown in the book As we can see conventional current is used in this figure. Here are some of my questions in response to this: Assume that a circuit was built exactly as modeled in this figure. If we open the switch and make this circuit an open circuit the bulb should still light up since electrons will flow from the negative terminal to the bulb and there is no switch to stop the electrons from reaching the bulb.
This is one of my objection to using conventional current in modeling circuits. Now assume that there's a resistor in place of that switch and an LED in place of that bulb i am sure i saw such a circuit somewhere. I can suppose that the resistor is there to prevent high voltage from reaching the LED so that it would not fry but again assuming that we make a circuit exactly like explained above the LED would still fry up because the current would reach the LED first and then the resistor.
Improve this question. Muneeb Muneeb 13 1 1 silver badge 3 3 bronze badges. We have to define current as flowing only in one direction in liquids not in both directions. If it flowed equally in both directions then it would add up to zero and current would not be conserved around a circuit.
In order to understand the idea of current flow in liquids we have to imagine that real negative charges flowing in one direction can be replaced by imaginary positive charges flowing in the other or vice-versa. This means we have 'two halves make a whole', rather than 'two halves cancel out'. So we have to deal with imaginary charges otherwise we can't teach current flow in liquids and gases properly.
If we have to develop this 'replace with imaginary charges' concept we might as well replace the right ones. The reason why electricity is important is that it helps us do lots of jobs.
The environmental impact of electricity is to do with the way this energy is converted from other forms. Transfers of electrical energy involve the movement of charge from high potential energy voltage to low potential energy voltage.
Electrical potential energy is defined in terms of the movement of positive charge. I know it's irritating but that's the way it's defined.
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