Chapter 8 Flashcards Preview

OCR Chemistry A level > Chapter 8 > Flashcards

Flashcards in Chapter 8 Deck (38)
Loading flashcards...
1

What is the SI units for electric current

Amperes(A)

2

What is electric current defined as?

Electric current is defined as the rate of flow of charge

3

What is the equation linking
-Current
-Charge
-Time

Q = I x t

4

What is the SI unit for charge

Coulombs

5

What is current derived from the equation Q = It

The amount of charge passing a given point in circuit per unit time

6

What is 1A equal to

1 C/s

7

What type of property is electric charge

A physical property

8

What are the 2 types of charges

1)Positive
2)Negative

9

What are ions described as when they referred by their charges

Relative charges

10

What is e

Elementary Charge

11

What is Elementary Charge

The relative charge a proton has e
(A electron has a charge of
-e)

12

What is the value of e

1.60 x 10^-19C

13

What is net charge

the charge on the object which is due to its gain or loss of electrons

14

How do you calculate the net charge on a object

Q = ne

Q-Coulombs
n-Number of electrons
e-Elementary charge

15

What is a charge carrier

carriers of charge(lol)

16

Name 2 charge carriers and where they operate

Electrons - Metals
Ions - Liquids

17

What is one way to make electrons to move in a metal wire

to make a positive end- this means all the electrons will flow towards to this direction

18

The greater the the rate of charge flow

the greater the electric current in a wire

19

What may a large current be due to?

1)A greater number of electrons moving past a given point each second
(e.g. a wire with a greater cross-sectional area)

2)A increase in the speed of the electrons moving faster through the metal

20

What is Conventional current

The direction of the electric current from the positive terminal to negative terminal

21

What is electron flow

The direction of the electric current from the negative terminal to the positive terminal

22

What is the name of the liquids that can carry current

Electrolyte

23

What are all the electrolyte

Molten ionic compounds
or
Ionic solution

24

What is the positive and negative electrodes called

1)Cathode(-)
2)Anode(+)

25

What is an ammeter used for

To measure the electric current at any point in a circuit

26

How much resistance does an ammeter have

Very little resistance
so it does not affect the current

27

Is the ammeter in parallel or in series

series

28

What does the conservation of charge state

That electric charge cannot be created nor destroyed

29

What does Kirchhoff's first law states

For any point in an electrical circuit, the sum of currents into that points is equal to the sum of currents out of the circuit

30

What is number density

It is the number of free electrons per cubic metre of material.

31

What does a higher number density mean

The greater the number density the better the electrical current

32

What are the 3 types of number density classification

1)Insulators
2)Semi-conductors
3)Conductors

33

What is the value of number density for conductors

Y x 10^28m-3

34

What is the value of number density for semi-conductors

Y x 10^17m-3

35

Why does appliances turn on instantly

This due to all the free electrons in the wire moving almost instantly

36

What is the equation linking
-Current
-Mean drift velocity
-Elementary Charge
-Number of electrons
-Cross sectional area

I = A x n x e x v

37

What is mean drift velocity

The average velocity gained by the free electrons of a conductor, with which the electrons get drifted under the influence of an electric field

38

What affect does the Cross sectional area of a wire have in the drift velocity

the smaller the Cross sectional area the higher the mean drift velocity