Charge and Current

Question 1

What is electrical current? state units

Answer 1

The rate of flow of charge. Measured in Amps.

Question 2

Give the symbol equation that relates charge current and time.(include units)

Answer 2

I = Q/T

I = Current(Amps)
Q = Charge(Coulombs)
T = Time(Seconds)

Question 3

in electricity, what does the “e” represent. What are the units for e.

Answer 3

e is the elementary charge and its units are coulombs.

Question 4

Give two examples of possible charge carriers.

Answer 4

Electrons - In metals.
Ions - In electrolytes.

Question 5

True or False. Current flows form negative to positive.

Answer 5

False. Conventional current is the “flow of positive charge”

Question 6

How can you measure the current in a circuit?

Answer 6

You can measure the current in a circuit by connecting an ammeter on series with the component.

Question 7

What is Kirchoffs First Law?

Answer 7

All of the current going into a junction is equal to all the current going out of a junction.

Question 8

What is meant by “Mean Drift Velocity”?

Answer 8

The average velocity of the charge carriers due to the applied electricl field.

Question 9

What equation uses the Drift Velocity to calculate electrical current

Answer 9

I =Anev

I = Current
A = Cross-Sectional Area
n = Number Density of Charge Carriers
e = Elemental Charge
v = Mean Drift Velocity

Question 10

What are the units of “Number Density of Charge Carriers” in the equation relating Current and Drift Velocity?

Answer 10

m^3

Question 11

Put Conductors, Semi-Conductors and insulators in order from highest “n”(Number Density of Charge Carriers) to lowest.

Answer 11

Highest - Conductors
Semi-Conductors
Lowest - Insulators