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Questions tagged [units]

A specified amount of a quantity (e.g. voltage, current, power, time, etc.) by comparison with which any other quantity of the same kind is measured or estimated. The standard system of units is the International System of Units (SI).

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Inductance Computed As Length in Historical Document

In "Formulas and Tables for the Calculation of Mutual and Self-inductance.", many equations compute the inductance of an arrangement as a length. For example, Equation 95, on p. 150, states,...
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18650 cell will use ______ amps every _____mins?

I am looking at how to utilise the BQ77915 Ultra-Low Power Primary Protector with Autonomous Cell Balancing by TI, using eight 18650 cells, each with a BQ77915 IC allowing 3 series - 5 series cells. ...
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Time Domain Normalization of the IMP23ABSU Microphone

I have tried to evaluate the analog microphone (IMP23ABSU) built into the STEVAL-STWINKT1B with the FP-SNS-DATALOG1 (HS-Datalogger). The values were exported as "raw values" (this is an ...
Tom's user avatar
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14 votes
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What does the "proportional symbol" (∝) mean when used as a time unit prefix?

In several datasheets for electronic components, I have seen a ∝ symbol used as a prefix for a time unit, usually seconds, writing as ∝s. As far as I know ∝ is not a valid SI prefix, so what does it ...
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I know the concept of per unit, but I don't know why am i wrong

A generator which apparent power is \$120MVA\$,and voltage is \$19.5kV,X_s=1.5p.u.\$. Now it is connected a transformer then connected to a transmission line. The rated value transformer is \$150MVA,...
user16266657's user avatar
5 votes
1 answer
314 views

Meaning of long term stability unit (µV/mo)

What does 'mo' stand for in a long term stability spec which has units of μV/mo?
Efanatic's user avatar
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In AC circuits, angles and frequency are measured in radians rather than degrees. Why?

Why do we use radians instead of degrees when working with alternators and the like? The maximum induced EMF in an alternator will be a completely different value if one calculated ω in degrees per ...
Jack's user avatar
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15 votes
5 answers
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Why is apparent power not measured in watts?

I'm studying circuit analysis. We are currently learning about AC circuits, particularly how power is calculated. I learned that there are four types of power: Complex, apparent, active and reactive, ...
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1 vote
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206 views

What is the meaning of "a" and "z" in capacitor value - Cadence Virtuoso

What is the meaning of "a" and "z" in capacitor value? Here is the image: I think "a" is angstrom, But I am not sure about it.
mohammad rezza's user avatar
12 votes
3 answers
4k views

Is "p" ever used to abbreviate pi in formulas?

I keep running into formulas in datasheets and articles that appear to be abbreviating pi as 'p'. An example from Ask The Applications Engineer-25: Op Amps Driving Capacitive Loads shows "1/2p...&...
Ben Froelich's user avatar
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533 views

Comparing scattering parameters in dB and magnitude+angle forms

We're trying to compare the scattering parameters from two parts (ADG902 and BF1101). Their datasheets use dB and mag/angle respectively. ADG902: BF1101: When trying to convert between the two, we ...
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6 votes
5 answers
24k views

Confused about MW to MWh conversion

I have various datasets of energy production in MW. I need to present everything in MWh. I need to know if my data is already by the hour (logging a value for each hour of each day of an entire year), ...
Bex's user avatar
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Battery capacity in mWh instead of mAh [duplicate]

I know that the capacity of a battery is expressed in mAh, i.e. A/s (international system of units). Today I used a command in PowerShell (*) in order to get the battery capacity, but the unit of ...
Gennaro Arguzzi's user avatar
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1 answer
153 views

Why are we able to ignore the henries, Hz, farads, siemens and ohms when calculating the characteristic impedance of a transmission line? [closed]

I have seen calculations, and every time we just take the coefficents of these values and end up calculating a simple complex number. The units all equate to various exponents of area, second, metre ...
ramose's user avatar
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1 answer
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Schematics Standard for Space between Value and Unit

On electrical schematics, is there a standard for whether there is a space between the numerical value and unit symbol? I can find standards that require it in general writing, but none that ...
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How to interpret the “surface power density” of a battery/capacitor

I’ve come across this research and one point of representing a power output confuses me: This enzymatic fuel cell is based on non-immobilized enzymes that exhibit a maximum power output of 0.8 mW cm−...
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1-dB compression point is in the range of -20 to -25 dBm

I am reading the Razavi's textbook RF Microelectronics 2nd edition p. 18. It says 1-dB compression point is typically in the range of -20 to -25 dBm (63.2 to 35.6 ...
sleeve chen's user avatar
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2k views

How to convert amplitude (V) to dB (V^2/Hz or V/sqrt(Hz) or V?)

I took the FFT of a signal and am currently plotting amplitude (V) vs. frequency (Hz). I'd like to change the Y-Axis units to dB. How would I go about doing this? What would be the units? It is from ...
Michael Joseph's user avatar
1 vote
3 answers
4k views

What is the difference between "Storage Temp", "Ambient Temp" and "Operating Temp" mean?

To my understanding, ambient temperature is the temperature of the surrounding area while the unit being worked on is powered. While operating temperature is the temperature of the unit itself under ...
Jaki Fingler's user avatar
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1 answer
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In semiconductor physics, how can we know which units to use for Boltzmann's constant?

I'm working through Example 3.9 from Sima Dimitrijev's Principles of Semiconductor Devices textbook, and I'm not sure how to know which units to use for k in solving for \$v_{th}\$ in part a. The ...
Jake Nixon's user avatar
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1 answer
116 views

capacitor unit is not specified

I am currently working on a circuit but I can't figure out the non-polarized capacitor values, since some of them are not clearly specified as unit magnitude. Some of them are: 100, 500, 180, 5.6, 56, ...
Kaan SOMUNCU's user avatar
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1 answer
90 views

How to recalculate amperes to amperes/micron (transistor characterstics)

I measured the transfer characteristic of P-type FET (so I have drain current versus gate voltage.) The authors usually present results in μA/μm (microampere/micron) versus V (volt.) Because I have ...
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How does Ohm disappear in noise/power spectral density unit?

Power spectral density is commonly expressed in Watts per Hertz (\$W \over Hz\$) or \$V \over \sqrt{Hz}\$. When I try to derive these for a resistor I get confused on the units. If we define noise ...
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How to convert dBm to V/m, A/m², and W/m²

Currently I am using a spectrum analyser (SA) Keysight N9020, with an antenna to get readings off the air. The reading on the SA gives a reading of a unit, dBm. However, I need to convert dBm to V/m, ...
arthur yeo's user avatar
1 vote
1 answer
337 views

What does Nu (ν) prefix mean?

Stumbled upon this in ZVN4525E6 datasheet: Zero Gate Voltage Drain Current (IDSS): 35 νA @ VDS = 250V, VGS = 0V The letter is U+03BD and it is not in any common unit prefixes that I know. My guess ...
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Units of PID for car' velocity?

I'd like to duple check from units of PID gains for the velocity of car. This my equations for PI controller V (m/s), kp (1/sec), ki(1/sec^2), kp' (radians/sec) , ki' (radians/sec^2) and kd (no unit)...
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2 answers
1k views

What is the meaning of VFS

I am working with a Dataq DI-1100 whose specs tout: "The analog inputs offer a fixed measurement range of ±10VFS..." VFS looks like a unit, but I find the language confusing. Researching turns up ...
Lorem Ipsum's user avatar
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3k views

How to convert between G and mV/g of sensitivity?

I cannot for the life of me understand how mV/g or LSB/g can be related to the g sensitivity. For example, how can I find 0.0025 G sensitivity accelerometer given the sensitivity in mV/g? I haven't ...
Seth Shill's user avatar
1 vote
2 answers
1k views

Analog values to ppm

How to transform a set of analog voltages from voltage to ppm/K? I have to use this to calculate the temperature coefficient of a bandgap. Is the derivative the same as the temperature coefficient ...
electricalEN's user avatar
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0 answers
67 views

Why is the Farad unit so large? [duplicate]

I have wondered this on and off for years, and was prompted to find out the answer: Any time I've seen capacitors, they're listed with milli- or pico-Farad ratings. I understand that, nowadays, we ...
KlaymenDK's user avatar
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3 answers
1k views

Compare white LED radiated optical power: lumens vs milliwatts

I'm trying to compare the brightness of various white LEDs, some of which are listed in lumens and others in milliWatts (this is milliwatts of optical output, not watts of electrical power consumption)...
Casey's user avatar
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2 votes
3 answers
325 views

Inconsistency in Values of Laplace Transformed Current when Changing Units

I was trying to convert the units of the following current in Time Domain and Complex Frequency domain (s-domain): $$ i(t)=20\cdot e^{-t}H(t)\,\,\,\,\,\text{[mA,ms]} $$ Where \$\text{[mA, ms]}\$ ...
Vinicius ACP's user avatar
6 votes
4 answers
3k views

What units are kpts?

I am parsing data from a Siglent SDS2000X oscilloscope. The first chunk (0x00 - 0x003) is for wave_length. The data sheet ...
Lorem Ipsum's user avatar
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2 answers
55 views

Can I represent the value by using this unit [closed]

I want to represent this value in a better way for my report. This value is 3.1x10^-4 the unit is dBi Can I rather represent this value using this: 310 udBi The u in udBi is micro dBi
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What are the units when solving Transmission Line iterativelly?

I would like to know the conductancee,\$C\$, and capacitance,\$G\$, of my lossy transmission line which is configured as an open circuit. In such a case, I know that the expression that defines the ...
ndarkness's user avatar
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1 answer
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Altium designer, changing from imperic to metrics primitives won't work?

I'm using a trial on Altium, where for I guess support ignores me (Altium Designer version 19.0.14). (I really hope it's better for real users if someone can confirm that, it would be most ...
user103776's user avatar
-2 votes
1 answer
131 views

Definition of \$ \frac{mm}{Ampere}\$ (unit of current sensitivity)?

I want to know how \$ \frac{mm}{Ampere}\$ (which is the unit of current sensitivity of PMMC instruments) is defined? i.e, How \$ mm \$ is defined in terms of \$ degrees\$ ? For eg.: \$ \frac{rad}{...
Suresh's user avatar
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2 answers
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What are these designations on a sensor datasheet?

I'm working with image sensor Anafocus Lince5M. In its datasheet there are some designations that I can't understand (underlined). What are these designations? And how to calculate threshold ...
ForceQuell's user avatar
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2 answers
1k views

\$pV/\sqrt {Hz}\$ in Power Spectral Density

I am trying to plot a Noise Spectral Density from 10 kHz to 1 MHz. The Graph shows a cure which at 1 MHz the noise is 76 pV/rootHz. I am unable to understand that unit definition here. Becuase the ...
dachu darshan's user avatar
5 votes
2 answers
604 views

Units of BJT parameters

Let's say the model is the Ebers-Moll model, but this obviously extends to other models: $$ I_{\mathrm{b}} = \frac{I_{\mathrm{s}}}{\beta_{\mathrm{f}}}\left(\mathrm{e}^{\frac{V_{\mathrm{be}}}{NV_{\...
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1 vote
2 answers
527 views

SENT protocol output unit is LSB. What does this mean?

I have read couple of datasheet of devices which uses SENT protocol. They define the output between 193 and 3896. The unit is LSB. I think that this does not mean least significant bit? Example: ...
Kono's user avatar
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How much maximum electricity bill (units) can be generated on 2 KW connection?

I have got a bill of approx 14000 Units (50000 INR) for a month on 2kW connection. As per my analysis and understanding, it can't be more than 2 * 24 HRs * 30 Days = 1440. I think electricity meter ...
Lovin's user avatar
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0 votes
2 answers
161 views

What other units can influence the way a wire glows than watt? [closed]

I have a vape device with a mod that lets me configure the power I want to operate it with and also as an additional setting that is called vape strength which can be set to soft/medium/hard. When ...
dhein's user avatar
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0 answers
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Pulse width modulation and textual expression of resulting stimulus level

So we have been using pulse width modulation (PWM) as a means to digitally change the driving voltage of vibration motors. Usually, afaik, the resulting voltage from PWM is expressed as %duty cycle ...
AliceD's user avatar
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4 votes
1 answer
1k views

Why do so many PCB-designers use non-metric units? [closed]

TLDR: Why do so many PCB-designers use non-metric units? Sorry for asking this closed question again: what is the advantage of non-metric units But I do not understand, and there is also no other ...
12431234123412341234123's user avatar
0 votes
1 answer
358 views

What's the difference between measurement resolution and digits per second in time measuring devices

In time/frequency counters/analyzers in technical specifications you can almost always find resolution and digits per second values next to each other. What is the difference?
Luke's user avatar
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2 answers
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What is the unit of measure for a region's power supply?

So, I'm casually perusing an old issue of Foreign Affairs magazine and encounter a paragraph concerning the ability of Brazil's electrical power generating plants to supply juice. Said paragraph ...
Digger's user avatar
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2 answers
159 views

Energy Consumption of AC Motors with same capacity and same hp

I have 2 3-phase motors with same capacity of 45kW, hp 60,rated Voltage is 415V, VFD 55kW connected separately to a Vessel Line that is used to mixing of few components.i.e, it looks like this. (I ...
dhinar1991's user avatar
1 vote
1 answer
385 views

Altium Symbol Wizard only in imperial

We have now got Altium 17 installed and set up, and I've used it to make various schematics. One feature of the software is the Symbol Wizard for creating our own symbols for different components. It'...
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6 votes
3 answers
13k views

Convert VAh to kWh

Sorry, this might be a stupid question as I'm not an electrical person. I'm analyzing an electricity consumption dataset and the consumption is measured by apparent energy (VAh). How do I convert ...
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