Chapter 3 - Electricity (3.1) Part 2

Question 1

Resistivity formula

Answer 1

Resistance = Resistivity x sample length / cross sectional area

Question 2

What is the resistivity of a material?

Answer 2

Same value as the resistance between two opposite faces of a cubic metre of the material

Question 3

What is drift velocity?

Answer 3

The slow overall movement of electrons (charges In a current)

Question 4

Equation for drift velocity?

Answer 4

Current = density of conduction electrons x the charge on carries x cross sectional area of conductor x drift velocity In conductor

Question 5

What will the conduction band be if the valence band is full?

Answer 5

Empty

Question 6

What will the conduction band be if the valence band is almost full

Answer 6

Almost empty

Question 7

What will the valence band be if the conduction band is almost full?

Answer 7

Almost empty

Question 8

When is a conduction hole formed and how does it move in the opposite direction to the current?

Answer 8

A conduction hole is formed when an electron leaves the conduction band leaving the atom with a hole which another electron will jump to leaving a hole in its conduction band effectively moving the hole in the opposite direction to current flow.

Question 9

What is a semiconductor

Answer 9

A conductor that have a lower resistivity than an insulator but higher than conductors . They usually only have small numbers of delocalised electrons free to conduct.

Question 10

What is the valence band

Answer 10

Range of energy amounts that electrons in a solid material can have which keeps them close to one particular atom

Question 11

What is the conduction band

Answer 11

A range of energy that electrons in solid material can have which delocalises them to move freely through the solid

Question 12

What is the critical temperature?

Answer 12

The temperature of which below the resistivity instantly drops to zero