2015-04-30 19:38:15 8 Comments

Sorry if this question is a bit broad but I can't find any info on this by just searching.

The equation q = neAL where L is the length of a conductor, A is the area of cross section, n is the number of charges and e is the fundamental charge. This equation clearly does not make sense from a dimensional point of view at first glance. So why is it true and why is it assumed true in most derivations for charge density in terms of drift velocity?

### Related Questions

#### Sponsored Content

#### 2 Answered Questions

### [SOLVED] How big of an area can a classical charge absorb an EM wave from?

**2020-03-05 08:24:20****Maximal Ideal****70**View**2**Score**2**Answer- Tags: electromagnetism electromagnetic-radiation charge

#### 2 Answered Questions

### [SOLVED] Why do outside charges not contribute to net flux through a surface, pt 2

**2019-01-30 00:40:32****theflightless****258**View**0**Score**2**Answer- Tags: electrostatics electric-fields charge gauss-law

#### 1 Answered Questions

### [SOLVED] continuity equation for uniform free charge distribution in electric field

**2017-08-15 12:52:00****user5419****166**View**0**Score**1**Answer- Tags: electromagnetism charge conductors

#### 4 Answered Questions

### [SOLVED] Why are electrical units (specifically, electrical current) considered a base unit?

**2017-05-13 04:04:11****gen-z ready to perish****998**View**6**Score**4**Answer- Tags: electric-current charge units si-units metrology

#### 1 Answered Questions

### [SOLVED] Dimensions of electric charge

**2017-05-17 11:59:00****Abhinav Dhawan****10399**View**1**Score**1**Answer- Tags: charge units measurements dimensional-analysis si-units

#### 2 Answered Questions

### [SOLVED] Charged body in hollow conductor : what is the role of insulators and how does the charge distribution change if insulators vs conductors are used?

**2016-10-29 09:22:55****K-Feldspar****1110**View**1**Score**2**Answer- Tags: homework-and-exercises electromagnetism charge conductors insulators

#### 1 Answered Questions

### [SOLVED] Absence of "charge" as a fundamental unit in natural system

**2016-08-02 18:16:58****Subho****116**View**2**Score**1**Answer- Tags: charge units dimensional-analysis metrology

## 1 comments

## @garyp 2015-04-30 19:43:02

$n$ is the particle density: Number of particles per cubic meter in SI units. $e$ would be the charge on a particle (Coulombs), here equal to the elementary charge (they could be protons). With that I think that you will see the the dimensions are correct.

## @Jaja 2015-04-30 19:45:07

Thank you very much. Similar symbols for similar equations can be quite cumbersome to work with. @BySymmetry commented first so I upvoted his comment. I will mark this as the answer when the time limit is up.

## @KidElephant 2015-04-30 20:03:39

A common convention is to use uppercase characters ($N$), for extrinsic properties (i.e., the

totalnumber), and lowercase characters ($n$) for intrinsic properties (number per unit volume). This way, $q = Ne$ is also valid, but less informative.