Charge and current 4.1

Question 1

What is electric current

Answer 1

The rate of flow of charge

Question 2

What does the ‘e’ represent and what are units

Answer 2

e in the elementary charge - proton has charge e+ and electron has charge -e
Units are coulombs

Question 3

Give two examples of possible charge carriers

Answer 3

Electrons - in metals
Ions - in electrolytes (aqueous solutions)

Question 4

Conventional current

Answer 4

Conventional current is the floe of positive charge - it is the opposite direction to the movement of the electrons in the circuit

Question 5

How can you measure current in circuit

Answer 5

with an ammeter connected in series with the component

Question 6

Kirchhoff’s first law

Answer 6

All the current going into a junction is equal to the current leaving the junction
charge is conserved

Question 7

mean drift velocity

Answer 7

average velocity of the charge carriers due to the applied elecrtci field
it has to be an average because they’re often moving randomly in all directions

Question 8

equation using drif velocity to calculate current

Answer 8

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

Question 9

put conductors, semiconductors and insulators in order from highest ‘n’ to lowest

Answer 9

Highest
conductors
semiconductors
insulators