Voltage - Wikipedia
The potential energy is a form of energy and the potential (and therefore voltage, when differences are taken) is defined as the potential energy. Voltage, electric potential difference, electric pressure or electric tension is the difference in electric potential between two points. The difference in electric potential between two points (i.e., voltage) in a static electric field is defined as the work needed .. In relation to "flow", the larger the "pressure difference" between two points. Jul 24, What is the relationship between constant force and velocity? Voltage is basically work needed to move a charge from point A to point B per unit charge.
Working on high voltage power lines Specifying a voltage measurement requires explicit or implicit specification of the points across which the voltage is measured. When using a voltmeter to measure potential difference, one electrical lead of the voltmeter must be connected to the first point, one to the second point. A common use of the term "voltage" is in describing the voltage dropped across an electrical device such as a resistor. The voltage drop across the device can be understood as the difference between measurements at each terminal of the device with respect to a common reference point or ground.
The voltage drop is the difference between the two readings. Two points in an electric circuit that are connected by an ideal conductor without resistance and not within a changing magnetic field have a voltage of zero.
Electric potential, voltage (article) | Khan Academy
Any two points with the same potential may be connected by a conductor and no current will flow between them. The various voltages in a circuit can be computed using Kirchhoff's circuit laws.
When talking about alternating current AC there is a difference between instantaneous voltage and average voltage. Instantaneous voltages can be added for direct current DC and AC, but average voltages can be meaningfully added only when they apply to signals that all have the same frequency and phase. Measuring instruments[ edit ] Multimeter set to measure voltage Instruments for measuring voltages include the voltmeterthe potentiometerand the oscilloscope.
- Work (electrical)
- Relation between work and voltage
The voltmeter works by measuring the current through a fixed resistor, which, according to Ohm's Lawis proportional to the voltage across the resistor. The potentiometer works by balancing the unknown voltage against a known voltage in a bridge circuit. The cathode-ray oscilloscope works by amplifying the voltage and using it to deflect an electron beam from a straight path, so that the deflection of the beam is proportional to the voltage.
Galvani potentialElectrochemical potentialand Fermi level Inside a conductive material, the energy of an electron is affected not only by the average electric potential, but also by the specific thermal and atomic environment that it is in. When a voltmeter is connected between two different types of metal, it measures not the electrostatic potential difference, but instead something else that is affected by thermodynamics.
The terms "voltage" and "electric potential" are ambiguous in that, in practice, they can refer to either of these in different contexts.
The force of gravity in newtons is then 3kg 9. The top of your bench is 1. How much work is required to pick up the transformer and place it on the bench?
What if the transformer is sitting on the floor in the next room, which is 20 meters away? Solution We determined in the previous problem that the force of gravity on a 6. The amount of work in joules is then 29N 1. It therefore takes the same amount of work, 35 joules.
Voltage Opposite charges attract. If we move a negative electron towards another electron we perform work because we are moving against an opposing force. Moving two electrons toward two other electrons requires more work because there is more opposing force.
We often need a convenient way to describe how much work is required to move charge from one point to another. That concept is voltage. If moving a positive charge from point B to point A requires positive work, then point A is said to have a positive voltage with respect to B. The relationship between the work required in joules, the amount of charge in coulombs, and the voltage in volts is: Since W and Q can be positive or negative, it stands to reason that V can be positive or negative also.
Problem It takes 1. Notice that this is opposite to the actual electron flow.
Electric potential, voltage
What is the voltage V across the resistor? Solution 1x electrons represent 1x We therefore conclude that the voltage at A is positive with respect to B by an amount equal to Thus there is a drop of volts across the resistor from the plate supply to the plate.
Power Power is a measure of the amount of work or energy being expended over time. When measured over the period of one second, the number of joules of sonic energy created from an Ampeg SVT with six push-pull power tubes cranked full blast is going to be far more than from a Champ 5E1.
By the same concept it takes no additional work to physically lift your Hiwatt quickly, but it takes more power because the work is performed over a shorter time period. When work is measured in joules and time is measured in seconds, then the power in watts is equal to the total work divided by the total time: Problem It takes you 2 seconds to steadily lift your 6.
What is the average amount of power you are expending as you lift it? Solution We determined earlier that it takes 35 joules of work to lift the transformer.