Electrical and diffusion current

Question 1

Symbol: Q

Answer 1

Charges

Question 2

Symbol: t

Answer 2

Time

Question 3

Symbol: I / Ix

Answer 3

Current

Question 4

Symbol: e

Answer 4

Charge of an electron

Question 5

Symbol: n

Answer 5

Number density

Question 6

Symbol: A

Answer 6

Cross-sectional area

Question 7

Symbol: Vdx / vdx

Answer 7

Mean drift velocity

Question 8

Symbol: J / Jx

Answer 8

Current density

Question 9

Symbol: μd

Answer 9

Drift mobility

Question 10

Symbol: Ex

Answer 10

Electric field strength

Question 11

Symbol: σ

Answer 11

Conductivity

Question 12

Symbol: De

Answer 12

Diffusion coefficient

Question 13

Symbol: x

Answer 13

Displacement

Question 14

Symbol: t / ∆t

Answer 14

Time

Question 15

Symbol: me

Answer 15

Mass of an electron

Question 16

Symbol: τ

Answer 16

Scattering time

Question 17

Symbol: N

Answer 17

Number of charges / Particles

Question 18

Symbol: V

Answer 18

Volume

Question 19

Symbol: a

Answer 19

Acceleration

Question 20

Symbol: ρ

Answer 20

Resistivity

Question 21

Symbol: R

Answer 21

Resistance

Question 22

Symbol: l with regards to resistivity

Answer 22

Length

Question 23

Symbol: Γ

Answer 23

Particle flux

Question 24

Symbol: l

Answer 24

Mean free path

Question 25

What is the number density?

Answer 25

This is the number of electrons per unit of volume

Question 26

What is mean drift velocity?

Answer 26

The average velocity of particles moving through a wire

Question 27

What is current density?

Answer 27

The rate of flow of charge per unit area

Question 28

What is current?

Answer 28

The rate of flow of charge

Question 29

What is drift mobility?

Answer 29

> The average drift velocity acquired per unit of electric field > A good measure of the quality of a wire

Question 30

What is conductivity?

Answer 30

> This is the inverse of resistivity

Question 31

What is the diffusion coefficient?

Answer 31

The diffusion coefficient is a measure of how well particles (here electrons) diffuse in a medium, and is the equivalent of conductivity

Question 32

What is the scatter time?

Answer 32

The mean time between collisions

Question 33

What is particle flux?

Answer 33

Number of particles / (Area × Unit of time)

Question 34

What is the mean free path?

Answer 34

This the average distance travelled by particles between collision

Question 35

3 Equations for current

Answer 35

``` I = dQ/dt I = Q/t Ix = enAVdx ```

Question 36

What are 4 equations for current density?

Answer 36

``` J = I/A J = enVdx J = enμdE J = σE ```

Question 37

What is the equation to calculate mean drift velocity?

Answer 37

Vdx = ( eE / me)τ

Question 38

How is the equation for mean drift velocity calculated?

Answer 38

``` F = qE = eE F = MA eE = me×A => A = eE/me Vdx = A×∆t Vdx = (eE/me)τ ```

Question 39

What is the equation for resistance in terms of resistivity?

Answer 39

R = ρl/A

Question 40

What are 3 equations for conductivity?

Answer 40

``` σ = 1/ρ σ = ne^2τ/me σ = neμd ```

Question 41

What are 2 equations for drift mobility?

Answer 41

``` μd = Vdx/E μd = eτ/me ```