Electricity

Question 1

current

Answer 1

the rate of flow of charge

Question 2

which way does conventional current flow?

Answer 2

positive to negative

Question 3

which way does electrons flow?

Answer 3

negative to positive

Question 4

mean drift velocity

Answer 4

average distance travelled by a charge carrier per unit time

Question 5

charge carrier

Answer 5

something which caries charge (electrons and ions)

Question 6

what does charge carrier density determine?

Answer 6

whether a material is a conductor, insulator or semiconductor
represented by n

Question 7

kirchoffs first law

Answer 7

the total current entering a junction is equal to the total current leaving a junction (conservation of charge)

Question 8

what is the link between current and charge carrier density? and resistivity?

Answer 8

the ability to carry a current increases with an increase in charge carrier density

the resistivity of a material is directly proportional to charge carrier density

Question 9

what is an anode?

Answer 9

positively charged electrode

Question 10

what is a cathode?

Answer 10

a negatively charged electrode

Question 11

what is a cation?

Answer 11

positively charged ions

Question 12

what is an anion?

Answer 12

negatively charged ions

Question 13

electric charge

Answer 13

a measure of how charged an object is
(measured in coulombs)

Question 14

quantised

Answer 14

a unit that can only be a certain value
eg. charge will always be a multiple of 1.6x10^-19

Question 15

electrolytes

Answer 15

liquids that can carry an electric current

Question 16

conductors

Answer 16

materials that have a high charge carrier density

Question 17

semiconductors

Answer 17

materials that have an intermediate charge carrier density
it also has a conductivity between a conductor and insulator (dependent on temperature)

Question 18

insulators

Answer 18

materials that have a low charge carrier density

Question 19

potential difference

Answer 19

the energy transferred per coulomb of charge
the work done per coulomb of charge that passes between two points

Question 20

electromotive forces

Answer 20

energy supplied per coulomb of charge
the amount of chemical energy converted to electrical energy per coulomb of charge when passing through a power supply

Question 21

thermionic emission

Answer 21

the emission of electrons through the action of heating

Question 22

resistance

Answer 22

a measure of how much a component resists the flow of charge

Question 23

ohms law

Answer 23

potential difference is directly proportional to current

Question 24

how do you work out the resistance of resistors in series?

Answer 24

add them together

Question 25

how do you work out the resistance of resistors in parallel?

Answer 25

1/total resistance= 1/R1+ 1/R2 +...

Question 26

resistance

Answer 26

how much an object opposes the flow of current

Question 27

what factors affect resistance?

Answer 27

length cross sectional area material temperature

Question 28

resistivity

Answer 28

a measure of how strongly a material opposes the flow of electric current

Question 29

conductivity

Answer 29

The degree to which a specified material conducts electricity (S/m)

Question 30

conductance

Answer 30

The degree to which an object conducts electricity (S)

Question 31

IV characteristics of a fixed resistor

Answer 31

-voltage is proportional to current -ohmic conductor -resistance is constant -behaves the same regardless of polarity

Question 32

IV characteristics of a filament lamp

Answer 32

-voltage is not proportional to current -non-ohmic conductor -resistance isn’t constant -behaves the same regardless of polarity -s shape on a graph

Question 33

IV characteristics of a diode

Answer 33

-voltage is not proportional to current -non-ohmic conductor -resistance isn’t constant -behaviour dependent on polarity -backwards l shape

Question 34

negative temperature coefficient

Answer 34

as temperature increases resistance decreases (in some semiconductors as temperature increases so does the charge carrier density)

Question 35

thermistor

Answer 35

as temperature increases resistance decreases (ntc)

Question 36

Fundamental frequency

Answer 36

The lowest frequency that can fit

Question 37

Kirchoff’s second law

Answer 37

The directed sum of the potential differences (voltages) around any closed loop is zero