Just like what we learnt before, an electrical current is the movement of electrons to one point to another. This movement can not be happening without involving energy transfer. We need something to make the electrons move. This energy transfer is what we have known as electric voltage.
Electric Voltage Definition
Electric voltage is also known as electromotive force (emf) or potential difference, also represents the battery illustration.
We will often meet a voltage variable V followed by two numbers or two alphabets, such as Vab or V12.
The voltage Vab represents the voltage between point a and b to move a unit of charge from a to b. This is electrical energy or work and can be calculated with a mathematical equation:
Where:
w = work (joules = J)
q = charge (coulombs = C)
The voltage is measured in volts (V). Volt itself can be represented as a potential difference between two points in the same circuit by 1 Joule of energy per coulomb (C) of charge passing through a circuit.
1 volt is equal to 1 joule/coulomb or 1 newton-meter/coulomb
Thus,
Voltage or potential difference is the required energy to make a unit charge moves through an element, measured in volts (V).
Observe the illustration of a potential difference below.
The voltage across an element connected to points a and b.
The symbol of positive (+) and negative (-) represent the current flow direction or voltage polarity.
How we interpret Vab can differ from each other, but commonly there are two interpretations:
- Point a has higher potential than point b
- Potential at point a with respect to point b is Vab
Thus,
In order to make it easier, we can observe the illustration below consisting of voltage across a resistor.
These two representations have the same voltage at 9 V but different polarity based on the polarity symbols.
- Figure A, point a has higher potential than point b at +9V.
- Figure B, point b has higher potential than point a at -9V.
The conclusion we can draw is:
- Figure A, there is a 9V voltage drop from a to b.
- Figure B, there is a 9V voltage rise from b to a.
Voltage drop is the decrease in voltage that occurs in an electrical circuit when current passes through a conductor or element.
Putting together every definition we have learnt recently, we can conclude everything about electrical voltage in an illustration below:
If the “level” of A and B are equal, there is no movement.
If the “level” of A is higher than B, the “water” will flow.
Just like an electric current, electrical voltage can also have constant value as a DC voltage (V) and dynamic value as an AC voltage (v).
The relationship between electrical voltage and electrical current can be used to calculate electrical power.
Voltage Definition in Electrical
Voltage or potential difference is the difference of potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to move a positive test charge from the first point to the second point.
Voltage is a somewhat electrical force that moves the negative electric charges (electrons) or current through a circuit across many circuit elements. This electrical energy can be absorbed by our components to generate different forms of energy.
Just as stated above, electrical voltage is also known as electromotive force (emf) that moves electrons through circuit elements.
The relationship between voltage and current can be easily calculated by Ohm’s Law.
Observe the simple electrical circuit below.
From our study of electrical current, in reality the electrons are moving from negative to positive terminal or polarity. For the sake of conventional purposes agreed worldwide, the current flow will be determined by the positive charge flow (red arrow) rather than electrons flow (black arrow).
Continuing from the illustration above, there are some works that are happening:
- Since it has a battery as a voltage source, it is a DC circuit. The electric current will start flowing through the circuit from positive to negative terminal as soon as the switch is closed.
- Since it is a closed circuit now, the voltage will generate electromotive force to push the electrons through the circuit from negative to positive polarity.
- The moment electric current flows through the lamp, it will turn on the lamp to make it glow.
- The current flows back to the voltage source’s positive polarity.
We can make a blinking LED circuit with a few tricks.
Of course, when talking about electrical current, the current direction is opposite of the electrons.
Just like stated above, there are two types of electricity, DC voltage and AC voltage.
The DC voltage has constant value over time while AC voltage has oscillating value over time. Whether it is AC or DC voltage, the measurement tool is the voltmeter.
To measure the voltage with a voltmeter we simply connect the positive and negative test leads or probes to nodes in an electrical circuit or leads of a component. Keep in mind to use a higher voltage scale for tool safety purposes.
Frequently Asked Questions
What is a voltage in electricity?
Voltage is a somewhat electrical force that moves the negative electric charges (electrons) or current through a circuit across many circuit elements. This electrical energy can be absorbed by our components to generate different forms of energy.
What is the definition of a volt?
Voltage or potential difference is the difference of potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to move a positive test charge from the first point to the second point.
What is voltage and its unit?
The voltage is measured in volts (V). Volt itself can be represented as a potential difference between two points in the same circuit by 1 Joule of energy per coulomb (C) of charge passing through a circuit.