Electric current

Question 1

What is current?

Answer 1

the rate of flow of charge in a wire or component

the current is due to the passage of charged particles (charge carrier)

e.g. electrons / ions

Question 2

What direction does current flow in a circuit?

Answer 2

from positive to negative

Question 3

What is the unit of charge and current?

Answer 3

current - ampere, A

charge, coulomb, C

Question 4

What is a coulomb equal to?

Answer 4

the charge flow in one second when the current is one ampere

Question 5

What is the equation for charge flow?

Answer 5

ΔQ = IΔt

Question 6

What are the properties of the insulator?

Answer 6

each electron is attached to an atom and cannot move away from the atom

when a volatage is applied across an insulator no current passes through because no electrons can move

Question 7

What are the properties of a metallic conductor?

Answer 7

some electrons are delocalised and the electrons are attracted towards the positive terminal of the metal

Question 8

What are the properties of a semiconductor?

Answer 8

the number of charge carriers increases with an increase of temperature

the resistance of a semiconductor therefore decreases as its temperature is raised

conduction is due to electrons that break free from the atoms of the semiconductor