Charge And Current

Question 1

What is an electric current?

Answer 1

An electric current is a net flow of charged particles

Question 2

What is the conventional current?

Answer 2

Conventional current is said to flow from positive to negative (opposite the direction of electron movement)

Question 3

Define electric current

Answer 3

An electric current is the rate of flow of charge

Current = charge / time

Question 4

Define the coulomb

Answer 4

One coulomb is the amount of charge which flows past a point in a circuit when a current of 1 ampere flows for 1 second

Question 5

State Kirchkoff’s first law

Answer 5

In a network of steady currents, the algebraic sum of the currents at any junction is equal to zero

Question 6

What is the conservation of charge?

Answer 6

Charge is conserved; the charge entering the junction is equal to the charge leaving

Question 7

State the equation for mean electron drift velocity

Answer 7

I = Anev
where I is the current
v is the mean drift velocity
A is the cross sectional area
n is the number density of charge carriers
e is the electronic charge (1.6x10^-19C)

Question 8

How does number density (n) vary with metals, semiconductors and insulators

Answer 8

The value n differs for the different classes of conductors, with metals having the most, semiconductors about ten billion (10^10) less and insulators few at all

Question 9

What is the value of the elementary charge (e)?

Answer 9

1.6x10^-19