What are watt and volt
1 volt is equal to a unit of voltage created by an electric current at the ends of a conductive device designed to produce 1 watt of heat at a constant electrical characteristic passing through the conductor. The volt characteristic is also defined as the potential difference between two measured points when a charge of one coulomb moves from point A to point B, when work of 1 joule is required.
Volts, watts and amps
1 W is an indicator of power at which work equal to 1 J is performed per second. It turns out that W is considered a derivative of two quantities. Power and voltage have a relationship:
1W = 1V*1A
Formulas
To have an idea of what power is, you need to think logically. If we assume that it is simply force, such a conclusion will be incorrect. To correctly evaluate a physical quantity, it is enough to know that power is the rate at which a device consumes energy.
For example, a lamp can produce bright or dim light, depending on the rate at which energy is consumed. If the brightness is higher, then the consumption is higher, and vice versa.
Attention! The power rating applies to all electrical appliances, but it is not always related to electricity. This is the main difference between the indicators.
Basic current values
Power also comes in:
- Thermal – determined by temperature parameters.
- Electrical – the indicator is taken into account in electrical appliances, including light bulbs.
- Mechanical, determined by the number of horsepower.
All of the above refers to physical characteristics.
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Definition based on the Josephson effect
Since 1990, the volt has been standardized by measurement using the time-dependent Josephson effect, which uses the Josephson constant as reference to the standard, stated by the 18th General Conference on Weights and Measures as[3]:
K_{J-90} = \frac{2e}{h} = 0.4835979 GHz/μV,
where e
— elementary charge,
h
— Planck’s constant
By this method, the value of a volt is unambiguously associated with the frequency standard set by a cesium clock: when a matrix consisting of several thousand Josephson junctions is irradiated with microwave radiation at frequencies from 10 GHz to 80 GHz, a well-defined electrical voltage arises, with the help of which voltmeters are calibrated[4] . Experiments have shown that this method is insensitive to the specific implementation of the installation and does not require the introduction of correction factors [5].
How are they designated?
W is a watt or a volt, some find it difficult to answer. The designation W was noted already in the century before last in Great Britain. The name of the measure was given in honor of the famous scientist, ideologist of the industrial revolution, James Watt, who was also the creator of the first steam engine.
He spent many years studying this indicator and used horsepower to measure it.
Volt is a unit named after the great physicist Alessandro Volta. A volt is defined as the difference in voltage or potential at the ends of a conductor, as well as between conductive sections of a circuit.
Designation of quantities:
- W – watt
- V – volt.
It is an accepted abbreviation (abbreviation) in the international system.
What is the difference between W and V (V and A)
What is the difference between a volt and an ampere: Volt is a unit of measurement of voltage, and watt is a unit of power. V is the difference created in the electrical potential across a wire line when a current of 1A dissipates a unit of power, i.e. voltage. The definition of voltage is that it is the potential of electricity between different points. Along with this, it is used to indicate the difference in potential energy of an electric charge between points. An energy source is a voltage that represents expended or lost energy.
About power
Attention! Voltage is hypothetically similar to the pressure created in a circuit, pushing electrons through.
The passage of current must be ensured on two paths. This characteristic is considered the total energy for moving the charge. The definition of voltage is based on the fact that negative charges are attracted to high values, and positive charges to low values.
W – speed of work. The speed is maintained at 1 meter per second against a constant reaction force of 1 newton. If we consider it in relation to electromagnetism, the unit is the rate of work done when 1 ampere passes through a potential difference of 1V. Watt is a measure of power.
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Power
Power is the energy flow with which energy is consumed. It happens that in the description of a device it appears instead of kW - kVA. To determine this value, you need to know what is measured in kVA.
No energy is expended to complete the work, but on the contrary:
- One of the factions becomes active, that is, it performs work or transforms into another form.
- The other faction is reactive. The energy is directed into an electromagnetic field.
Attention! These quantities are different, despite the same proportionality. To avoid confusion, the indicator is measured not in watts, but in volt-amperes.
Mechanical power
Electric potential
A charge introduced into an electric field has a certain amount of energy, i.e., the ability to do work. To characterize the energy stored at each point of the electric field, a special concept was introduced - electric potential. The potential of the electric field at a given point is equal to the work that the forces of this field can do when moving a unit of positive charge from this point outside the field.
Returning to the analogy with the gravitational field, we can find that the concept of electric potential is akin to the concept of the level of various points on the earth's surface. That is, as we will consider below, the work of raising a body above sea level depends on how high we raise that body, and similarly, the work of moving one charge away from another depends on how far these charges are.
Let's imagine the hero of the ancient Greek world, Sisyphus. For his sins in earthly life, the gods sentenced Sisyphus to do hard, meaningless work in the afterlife, rolling a huge stone to the top of a mountain. Obviously, to lift a stone halfway up the mountain, Sisyphus needs to spend half as much work as to lift the stone to the top. Then the stone, by the will of the gods, rolled down the mountain, doing some work. Naturally, a stone raised to the top of a mountain of height H
(level H), when descending, will be able to do more work than a stone raised to level
H
/2. Sea level is generally considered to be the zero level, from which altitude is measured.
By analogy, the electrical potential of the earth's surface is considered zero potential, that is
ϕEarth = 0
where ϕEarth is the designation of the Earth’s electrical potential, which is a scalar quantity (ϕ is a letter of the Greek alphabet and is read as “phi”).
This quantity quantitatively characterizes the field’s ability to do work (W) to move some charge (q) from a given point in the field to another point:
ϕ = W/q
The SI unit of electrical potential is the volt (V).
Visitors to the Canadian Science and Technology Museum spin a large squirrel wheel, which spins a generator that powers a Tesla transformer (pictured right), which in turn creates a high voltage of several tens of thousands of volts, enough to puncture the air.
What voltage is measured in volts and watts
Voltage in watts or volts is measured according to individual criteria. Voltage measurements are carried out in Volts, and in the drawings it is indicated by the letter V. The voltage is measured by a device - a voltmeter. The latest devices may be:
- Analog.
- Digital.
The first ones are more accurate.
Portable devices have voltmeters built into them, and these tools are used by electricians. Analog devices are installed on electrical panels: switchboards and generators. The latest equipment comes complete with digital meters.
The voltage value in accordance with international standards is established:
- Kilovolt – kV.
- Millivolt – mV.
- Volt - V.
- Megavolt - MV.
- Microvolt - µV.
Voltage measurements
Important! Power is measured in watts (kilowatts). This value is directly proportional to the voltage, as well as to the magnitude of the current. The main difference is the designation of established indicators, according to the measurement system.
How to convert volts and watts and vice versa
To correctly complete the task associated with converting volts to watts, you can follow the following algorithm:
- You need to find the power value in the operating manual of the electrical appliance. Companies often indicate this value in volt-amperes. This symbol indicates the maximum amount of electricity consumed. So it is equal to the power value.
- Determine the efficiency of the power source based on the design features and the number of devices connected to it. As a rule, this coefficient is set in the range from 0.6 to 0.8.
- Convert current-voltage indicators to W: find out the active power of energy equipment designed to supply uninterruptible power.
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Important! Calculate the number of watts by multiplying volt-amperes by efficiency.
Visual representation of voltage and current
- Conversion from W to V follows the reverse pattern: watts must be divided by the efficiency factor.
When choosing a power source from the manufacturer, it is not always clear how much power the device produces. Therefore, it is recommended to study the technical parameters specified in the instructions in order to carry out the correct conversion from one value to another.
Voltage scale
- The lowest measured voltage is about 10 nV.K: Wikipedia: Articles without sources (type: not specified) [ source not specified 3008 days
] - The output voltage on the magnetic head of a cassette recorder is 0.3 mV[6].
- The potential difference across the neuron membrane is 70 mV.
- NiCd battery - 1.2 V.
- Alkaline cell - 1.5 V.
- Lithium iron phosphate battery (LiFePO4) - 3.3 V.
- Charger for mobile phones – 5.0 V.
- Battery "Krona" - 9 V.
- Car battery - 12 V (for heavy trucks - 24 V).
- Household voltage in Russia is 127 V, 220 V (single-phase), 380 V (three-phase).
- Voltage in industrial networks - 380 V (three-phase), 380 V (single-phase), 660 V (three-phase)
- The voltage in the contact network of a tram and trolleybus is 600 V (660 V) (direct current).
- The voltage of the contact rail in the subway is 825 V (direct current) K: Wikipedia: Articles without sources (type: not specified) [ source not specified 2995 days
]. - Electrified railways - 3 kV (direct current), 25 kV (alternating current).
- Main power lines - 110, 220, 330, 500, 750 and 1150 kV.
- The maximum voltage on power lines (Ekibastuz-Kokshetau) is 1.15 MV.
- The highest DC voltage obtained in the laboratory using a pelletron is 25 MV.
- Lightning - from 100 MV and above.
