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Physics Flashcards

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1
Q

What does a substance that loses electrons become

A

Positively charged

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2
Q

What happens if charges in an ion:
Are the same.
Opposite.
One is charged the other isn’t.

A

Repel
Attract
Attract

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3
Q

How can you tell if an insulator is charged

Two

A

It attracts small pieces of dust and paper

When a balloon is charged it sticks to a wall

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4
Q

Two problems with static

A

Dust and dirt are attracted to insulators such as computer screens

Clothes made from synthetic materials cling to each other and to the body

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5
Q

Two dangers of static

A

If there are flammable gases or a high concentration of oxigen a spark could ignite the gases and cause an explosion

If you touch something with an electric charge on it it gives you a shock and could cause a heart attack

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6
Q

Safety measures from static shocks

A

An object that might be charged is connected to the earth by a wire so any charge disapaits

In a factory workers stand on an insulator matt so charges can’t be earthed through them

Lorries containing flammable liquids and gases are connected to the earth through earth through earth wire befor being loaded

When an aircraft is fueled static can build up this can causes sparks which can ignite the fuel a wire is used to earth the aircraft before it is fueled

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7
Q

What are five examples of uses of static

A

Photocopiers and laser printers

Defibrillators

Electrostatic dust precipitators

Paint spraying powder coats

Insecticide sprays

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8
Q

What is an electrical currant

A

A flow of electrical charge

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9
Q

How does a conventional current flow

A

From the post stove side of the terminal to the negative side

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10
Q

In what direction do electrons move compared to the conventional current

A

The opposite way

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11
Q

How do electrical conductress differ to insulators

A

Their electrons can move from atom to atom

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12
Q

What is the unit of charge

A

The coulomb c

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13
Q

What is the uk mains supply’s voltage and frequency

A

230v

50hz

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14
Q

What happens to the current when the components are connected in series

A

The current is the same

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15
Q

What happens to the current of components connected in parallel

A

It is shared

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16
Q

What is the word used to describe the fact that the total current going into the split in a parallel circuit is the same as the one going out

A

The current is CONSERVED

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17
Q

What is the unit for current

A

Amperes

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18
Q

How must an ammeter be connected into a circuit

A

In series

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19
Q

What does a substance that gains electrons become

A

Positively charged

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20
Q

How must a voltmeter be connected to a circuit

A

In parallel

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21
Q

If two 1.5v cells are connected in series in opposite direction what is the voltage

A

0

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22
Q

If two 1.5v batteries are connected in series facing the same direction what is the voltage

A

3v

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23
Q

What is the relationship between energy transferred, potential difference and charge

A

Joules=voltage x coulombs (charge)

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24
Q

What is the unit for resistance

A

Ohms

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25
Q

What do resisters do in a circuit

A

Reduce the amount of current flowing

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26
Q

What is the name for a variable resistor

A

Rheostat

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27
Q

What happens to the current as you increase the potential difference

A

It increases

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28
Q

What is the equation for the relationship between resistance voltage and current

A

Resistance=voltage/current

R= v/a

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29
Q

What is the relationship between voltage current and resistance

A

Voltage=current x resistance

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30
Q

What is ohms law

A

The result that the current flowing through a resistor=the voltage across the resistor. Providing the temp stay the same

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31
Q

What does it mean if the current flowing through a resistor is directly proportional to the voltage across it

A

It follows ohms law

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32
Q

Does a filament lamp follow ohms law

A

No, the resistance increases as the current increases

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33
Q

What is the current potential difference graph for a diode

A

A straight line then a steep line going to the right

This is because diodes have a very high resistance one way so it can only flow the other way

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34
Q

What is a thermistor

A

Thermistors are temperature sensors their resistance decreases as the temperature increases

A use is in fire alarms

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35
Q

What is the symbol for a thermistor

A

A rectangle in the circuit with a line underneath it which then turns and goes through the box at a 45 degree angle

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36
Q

What are ldr’s

A

Light dependant resistors. Used in automatic security lights. Their resistance decreases as the light intensity increases

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37
Q

What is the symbol for an ldr (light dependant resistor)

A

A rectangle in the circuit with a circle around it. Stows point to it in accordance to where the light is coming from

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38
Q

What is the energy transfer I’m a resistor

Plus two uses

A

Some of the energy from the electrical current gets turned into heat

Heating water in an electric kettle
Electric fires

39
Q

What causes the heat transfer in wires

A

The free flowing electrons colliding with ions in the lattice structure of the metal each collision causes heat to transfer to the lattice

40
Q

What happens to a resistor as it’s temperature increases.

A

It’s resistance increases

41
Q

What is diplacement

A

Distance traveled in a straight line

42
Q

What is the velocity

A

The velocity of an object is its speed in one pert inculcate direction

43
Q

What are the four vector quantities of a moving object

A

Displacement
Velocity
Acceleration
Force

44
Q

How do you find the distance traveled on velocity time graphs

A

The area below the line

45
Q

What are the two factors in the size of acceleration

A

The size of the resultant force
Doubling the resultant force doubles the acceleration

The mass
Doubling mass halves the acceleration

46
Q

What is the strength of gravity on earth

A

Ten newtons per kilogram

47
Q

The three stages of falling

A

Acceleration downwards of the object no air resistance
Resultant force is acting downwards

Object gains speed weight stays the same but air resistance increases
Resultant force is acting downwards

Weight is balanced with air resistance there is no resultant force reaches terminal velocity

48
Q

How do seat belts prevent injury in a car crash

A

Stop you moving inside the car

Stretch slightly to reduce the time taken for the body to reach zero so reduces forces on it

49
Q

How do airbags help you survive a car crash

A

Increase the time for the heads movement to reach zero to reduce forces on it

Act as a cushion to stop cuts

50
Q

What two things the amount of work done depend on

A

The size of the force on the object

The distance the the object moves

51
Q

What is the relationship between work done by brakes and the loss in kinetic energy

A

Work by brakes=loss in kinetic energy

52
Q

What happens to the braking distance of a car if it’s speed doubles

A

It quadruples

53
Q

What does power measure

A

How quickly work is being done

54
Q

What is the measure of power

A

Watts

55
Q

What does the amount of gravitational potential energy depend on

A

Mass

Height above ground

56
Q

What are the gravitational field strengths of the earth moon and Jupiter

A

Earth 10n

Moon1.6n

Jupiter26n

57
Q

What are the dependant values on the size of kinetic energy in a moving object

A

Speed and mass

58
Q

What is the relationship between work done by brakes and the loss in kinetic energy

A

They are equal

59
Q

What is an example of conservation of energy

A

Newtons pendulum

60
Q

What makes a material radioactive

A

The nucleus of the atom is unstable and can decay by giving off radiation in the form of alpha particles beta particles or gamma rays

61
Q

What is used to measure radioactivity

A

A Geiger counter

62
Q

What is the activity of a radioactive material measured in

A

Becquerels

63
Q

What is the activity of a radioactive material

A

The number of nuclei that decay and give off radiation every second

64
Q

What is an alpha particle made of

A

Two protons and two neutrons, same as a helium nucleus

65
Q

What is a beta particle made of

A

A fast moving electron

66
Q

What is a gamma ray made of

A

High energy electromagnetic radiation

67
Q

How well does gamma ionise

A

Weakly

68
Q

How well do alpha particles ionise

A

Very well

69
Q

How well do beta particles ionise

A

Medium

70
Q

What happens after alpha decay

A

A new element is formed two places lower in the periodic table

71
Q

What happens after beta decay

A

The nucleus has one more proton and one less neutron

72
Q

Steps of fission 4

A

Neutron fired into nucleus

Neutron hits nucleus

Nucleus splits into smaller nuclei called daughter nuclei and releases two or three more neutrons

The released neutrons hit more uranium nuclei

73
Q

Where is the most dangerous nuclear waste stored

A

Glass like blocks deep in the ground

74
Q

How else can a nuclear reactor be used

A

Can make other nuclei radioactive because they absorb the neutrons which makes their nuclei unstable

These are used as tracers in hospitals

75
Q

How do control rods reduce reaction speeds and what are they made of

A

When hit by a neutron the daughter nuclei make two or three extra neutrons, this reaction is a chain reaction and if not controlled would easily spiral out of control
Control rods are made of boron which absorbs the neutrons, this slows down the reaction as less neutrons are hitting new nuclei

The control rods are lowered to slow the reactiOn down and raised to speed it up

76
Q

Two steps of fusion

A

Two hydrogen atom collide and fuse together

The hydrogens fuse to produce a helium atom and energy

77
Q

What is the difficulty of nuclear fusion

A

Both hydrogen atoms are positively charged which causes electrostatic repulsion so it has to be very hot for the nuclei to coliseum as they then move faster

Pressure and heat have to be very high and are more expensive to produce than the energy made by fusion

78
Q

Why was cold fusion never considered to work

A

Many attempts to reproduce the results failed

So it did not pass the peer review

79
Q

How do rocks emit radiation

A

Radon gas emited

80
Q

How is alpha radiation used

A

Smoke detectors

Americium releases alpha which ironises the air in a detector smoke from fire ionises differently and causes the alarm to go off

81
Q

What are the uses of beta two

A

Medical tracers certain chemicals concentrate in damaged or diseased parts of the the body radiation detectors are placed around the body to build an image of the inside

Measuring thickness of materials

The thicker the material the more radiation is absorbed and the less radiation reaches the detector
The detector then sends signals to the machine to decrease the size of the material

82
Q

Uses of gama

A

Treatment of cancer

Sterilising medical equipment no heat so plastics can be sterilised

83
Q

What does the rate of nuclear decay depend on

A

The type of material

The number of un decayed nuclei present the greater the rate

84
Q

How is carbon fourteen formed

A

Cosmic rays hitting he atmosphere

85
Q

How is carbon dating done

A

Using the half life of carbon 14 we can judge the age of something as the amount of carbon 14 on earth always stays the same

86
Q

How is the age of rocks found

A

The ratio of uranium to lead

As the rock gets older there is more lead available

87
Q

What accounts for the most background radiation

A

Radon gas

88
Q

Dangers of ironising radiation on the body

A

Breaks molecules into fragments
The ions then react with other molecules in cells

Charged particles can react with DNA which causes mutations and cancer

89
Q

Five precautions around radioactivity

A

Using tongues to pick up sources

Surveys kept in lead containers

Sources never pointed at people

Protective clothing

Exposure times limited

90
Q

Disadv to nuclear energy

A

Non renewable

If accident large amounts of radiation released

Nuclear waste stays radioactive for thousands of years

91
Q

How is low level waste disposed

A

Put in drums and submerged in concrete

92
Q

How is intermediate level waste disposed

A

Mixed with concrete then put in stainless steel drum

93
Q

How is high level n waste stored

A

Stored under water in large pools for 20 years then put in underground store where air can circulate and cool it

Chem (9 decks)

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