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OCR Chemistry A level > Chapter 8 > Flashcards

Chapter 8 Flashcards

Charge and Current

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1
Q

What is the SI units for electric current

A

Amperes(A)

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2
Q

What is electric current defined as?

A

Electric current is defined as the rate of flow of charge

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3
Q

What is the equation linking

  • Current
  • Charge
  • Time
A

Q = I x t

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4
Q

What is the SI unit for charge

A

Coulombs

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5
Q

What is current derived from the equation Q = It

A

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

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6
Q

What is 1A equal to

A

1 C/s

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7
Q

What type of property is electric charge

A

A physical property

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8
Q

What are the 2 types of charges

A

1) Positive

2) Negative

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9
Q

What are ions described as when they referred by their charges

A

Relative charges

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10
Q

What is e

A

Elementary Charge

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11
Q

What is Elementary Charge

A

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

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12
Q

What is the value of e

A

1.60 x 10^-19C

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13
Q

What is net charge

A

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

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14
Q

How do you calculate the net charge on a object

A

Q = ne

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

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15
Q

What is a charge carrier

A

carriers of charge(lol)

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16
Q

Name 2 charge carriers and where they operate

A

Electrons - Metals

Ions - Liquids

17
Q

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

A

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

18
Q

The greater the the rate of charge flow

A

the greater the electric current in a wire

19
Q

What may a large current be due to?

A

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
Q

What is Conventional current

A

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

21
Q

What is electron flow

A

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

22
Q

What is the name of the liquids that can carry current

A

Electrolyte

23
Q

What are all the electrolyte

A

Molten ionic compounds
or
Ionic solution

24
Q

What is the positive and negative electrodes called

A

1) Cathode(-)

2) Anode(+)

25
Q

What is an ammeter used for

A

To measure the electric current at any point in a circuit

26
Q

How much resistance does an ammeter have

A

Very little resistance

so it does not affect the current

27
Q

Is the ammeter in parallel or in series

A

series

28
Q

What does the conservation of charge state

A

That electric charge cannot be created nor destroyed

29
Q

What does Kirchhoff’s first law states

A

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
Q

What is number density

A

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

31
Q

What does a higher number density mean

A

The greater the number density the better the electrical current

32
Q

What are the 3 types of number density classification

A

1) Insulators
2) Semi-conductors
3) Conductors

33
Q

What is the value of number density for conductors

A

Y x 10^28m-3

34
Q

What is the value of number density for semi-conductors

A

Y x 10^17m-3

35
Q

Why does appliances turn on instantly

A

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

36
Q

What is the equation linking

  • Current
  • Mean drift velocity
  • Elementary Charge
  • Number of electrons
  • Cross sectional area
A

I = A x n x e x v

37
Q

What is mean drift velocity

A

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
Q

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

A

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

OCR Chemistry A level (2 decks)

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