Chapter 8 - Charge and Current

Question 1

What is Current?

What does 1A represent?

What is the equation for Current?

Answer 1

The rate of flow of charge in the SI unit A, Ampere

1A is the same as 1C passing through a point in 1 second

I = Q/T

Question 2

What is Charge?

What does 1C represent?

How is Charge formed?

Answer 2

A positive/negative quantity a particle carries. It is quantized and represented by the unit C

1C is the charge that passes through a point in 1 second when there’s 1A of current

When something gains or looses electrons

Question 3

What is Conventional Current

What is Electron Flow?

Answer 3

(A flow of charge). The assumption that charge flows from + to -

(A flow of charge). The real flow of charge from - to + terminal

Question 4

What is a Charge Carrier?

Examples of Charge Carriers

Answer 4

Delocalized Charged particles which carries Charge. C is quantized by the total charge of all the charge carriers

Electrons, Protons, +/- ions (in liquid and gases and can travel in either direction of charge)

Question 5

What is a Conductor?

What is an Insulator

Answer 5

A material that has Charge Carriers per unit volume that flows through it

A material with with no charge carriers

Question 6

What is Mean Drift Velocity?

What is the Equation for Mean Drift Velocity?

Answer 6

It is the average velocity a charge carrier travels in a wire per second as they collide with the lattice

I = nAve
I = Current (A)
n = Number Density of Charge Carriers (m^-3)
A = Cross Section Area (m^2)
v = Mean Drift Velocity (ms-1)
e = Charge per Carrier

Question 7

What is Kirchhoff’s 1st Law?

Answer 7

Current into Junctions = Current out of the Junctions (Sum of current in = Sum of Current Out)

Question 8

How could you increase the current in a wire?

Answer 8

Increase the charge carriers so there’s more Charge, done by using Semi-Conductor

Increasing the Cross Section of a Wire

Increasing the Mean Drift Velocity by increasing the Potential Difference

Question 9

What is the Charge on an electron?

What is the mass of an electron?

What is the formula for Number of electrons?

Answer 9

1.6*10^-19C

9.11*10^-31kg

n = Q/e
n = number of electrons
Q = Total Charge
e = elementary charge

Question 10

What is the elementary charge?

Answer 10

Smallest unit of charge. The charge all the charge carriers have which the total charge is quantized by