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Science 30 > physics > Flashcards

physics Flashcards

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1
Q

what does negatively charged mean?

A

more electrons than protons

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2
Q

what does positively charged mean?

A

less electrons than protons

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3
Q

can electrons transfer?

A

yes

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4
Q

can protons transfer?

A

no

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5
Q

what kind of charges repel?

A

like charges

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6
Q

what kind of charges attract?

A

opposite charges

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7
Q

what is the unit of charge?

A

coulomb (C)

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8
Q

what are conductors?

A

an object that allows electrons to move through freely (conducts electric current)

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9
Q

what are insulators?

A

objects that do not conduct electric current

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10
Q

what is a field?

A

a region of influence around a source

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11
Q

what is a test body?

A

an observable object that experiences a force due to the field

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12
Q

what is a gravitational field?

A

surrounds an object that has mass and exerts force on other objects with mass

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13
Q

what is an electrical field?

A

surrounds an object that has charge and exerts force on other objects with charge

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14
Q

what is a magnetic field?

A

surrounds a magnet and exerts force on other magnets and metals

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15
Q

what are vectors?

A
  1. gravitational field
  2. electrical field
  3. magnetic field
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16
Q

what is field strength?

A

the strength of a field on a test body

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17
Q

what is the effect of distance on field strength?

A

field strength decreases as distance from the source increases

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18
Q

what are field lines?

A

used to describe the direction of the field and the strength – the denser the field lines, the stronger the field

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19
Q

what is the direction of force in a gravitational field?

A

towards the centre of the source

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20
Q

how are electrical fields created?

A

created when electrons are transferred

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21
Q

what is the direction of force in an electrical field and magnetic field?

A

the direction of force follows the electrons

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22
Q

what is an electric current?

A

a flow of electric charge from one point to another

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23
Q

what are all magnetic fields generated by?

A

moving charges

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24
Q

why do most magnetic fields end up cancelling out?

A

because the electrons don’t align

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25
Q

what produces a permanent magnet?

A

when it is impossible to align the atoms so the fields line up and reinforce each other

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26
Q

what does a motor do?

A

changes electrical energy into mechanical energy

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27
Q

what does a generator do?

A

changes mechanical energy into electrical energy

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28
Q

what is an armature?

A

an electromagnet (a coil of wire around a piece of metal)

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29
Q

what is a commutator?

A

site of electron transfer

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30
Q

what is a shaft?

A

the rotating axis

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31
Q

what is a brush?

A

make contact with the commentator for transfer of electric current

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32
Q

what is a field magnet

A

a permanent magnet

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33
Q

what are the two types of power current?

A
  1. alternating current

2. direct current

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34
Q

what is electromagnetic induction?

A

production of electrical energy in a conductor as a result of a moving magnetic field

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35
Q

what are responsible for flipping the electric field in a motor?

A

the commutator and the brushes

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36
Q

what is direct current?

A

a flow of charges that does not increase or decrease and flows in a single direction

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37
Q

what is an alternating current?

A

a flow of charges that reverses direction at regular intervals

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38
Q

what type of commutator does a DC require?

A

a split ring commutator (has gaps)

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39
Q

what type of commutator does an AC require?

A

a slip ring commutator (no gaps)

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40
Q

what is a circuit?

A

a closed loop for moving charges

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41
Q

what is a series circuit?

A

a single path for electrical current – charges have to flow through one device before passing onto the next

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42
Q

what is a parallel circuit?

A

more than one path available – current divides allowing the current to pass through different devices at the same time

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43
Q

what is voltage?

A

the electric potential difference between two points

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44
Q

what is resistance?

A

opposition to the passage of current through a conductor

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45
Q

how is heat generated?

A

through friction between electrons

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46
Q

what does resistance depend on?

A

the length, thickness and type of wire

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47
Q

what does electric current depend on?

A

the number of electrons that pass a point in a circuit every second

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48
Q

what is current measured in?

A

amps

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49
Q

what is electromotive force?

A

the force required to make the current flow

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50
Q

what value stays constant in a series circuit?

A

current

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51
Q

what value stays constant in a parallel circuit?

A

voltage

52
Q

what is power?

A

the rate at which energy is used

53
Q

what is power directly related to?

A

current and voltage

54
Q

what is a multimeter?

A

a device used to measure quantities in a circuit

55
Q

what must you do before measuring any quantity?

A

make sure the dial is set to measure the desired quantity

56
Q

to measure what quantity does a multimeter have to be set up in series?

A

to measure current

57
Q

to measure what quantity does a multimeter have to be set up in parallel?

A

to measure voltage

58
Q

why is there large potential for power loss in electricity distribution?

A

because current must flow through kilometres of wire

59
Q

what are transformers?

A

devices that transform AC voltage from low to high or vice versa

60
Q

what are the three main parts of a transformer?

A
  1. soft iron core
  2. primary coil
  3. secondary coil
61
Q

what is the primary coil of a transformer?

A

connected to the input energy

62
Q

what is the secondary coil of a transformer?

A

connected to the device (outputs energy)

63
Q

what are the two types of transformers?

A
  1. step up

2. step down

64
Q

what is a step up transformer?

A

the secondary coil is wrapped more times than the primary so the voltage is increased

65
Q

what is a step down transformer?

A

secondary coil is wrapped less times than the primary so the voltage is decreased

66
Q

what are the characteristics of AC?

A
  • high voltage
  • low amperage
  • less energy lost as heat
67
Q

who created AC?

A

Tesla

68
Q

who created DC?

A

Edison

69
Q

what are the characteristics of DC?

A
  • low voltage
  • high amperage
  • more energy lost as heat
70
Q

what are the advantages of AC?

A
  • can travel long distances without significant power loss

- can be easily changed into higher or lower voltage

71
Q

what are the advantages of DC?

A
  • ideal for small appliances that need portability
  • can be used as backup power
  • lower voltage –> safer
72
Q

what type of current can transformers be used on?

A

alternating current

73
Q

what are the disadvantages of AC?

A

greater risk of electrocution due to high voltage

74
Q

what are the disadvantages of DC?

A
  • most effective when the source is connected to appliance

- less effective over long distances

75
Q

what is the electric field of AC?

A

direction of current alternates

76
Q

what is the electric field of DC?

A

direction of current stays the same

77
Q

what four devices are used to increase safety when using electrical energy?

A
  1. circuit fuses
  2. polarized plugs
  3. breakers
  4. ground wiring
78
Q

what is a circuit fuse?

A

a safety device that protects electrical circuits from over current; it has a metal wire/strip that melts when too much current flows through it

79
Q

what are polarized plugs?

A

there are both neutral and hot wires and a directional flow to how the current runs through the system

80
Q

what are breakers?

A

an electrical switch that will interrupt current flow after detection of a fault

81
Q

what is ground wiring?

A

a wire acting as a conductor from an electric circuit to a ground

82
Q

what is electromagnetic radiation?

A

a changing electric field and a changing magnetic field travelling at right angles to each other

83
Q

what is EMR emitted from?

A

the stars (eg. the sun)

84
Q

in what shape does EMR travel in?

A

waves

85
Q

what are transverse waves?

A

the vibrations are perpendicular to the direction the wave travels

86
Q

what is frequency?

A

how often a cycle occurs per second

87
Q

what is frequency measured in?

A

hertz (Hz)

88
Q

what are characteristics of high frequency?

A
  • short wave lengths
  • more dangerous
  • ionizing radiation
89
Q

what are characteristics of low frequency?

A
  • long wave length
  • less dangerous
  • non-ionizing
90
Q

what are photons?

A

bundles of light energy that move at the speed of light

91
Q

what do solar flares from the sun emit?

A

xrays, gamma rays and radio waves

92
Q

who proposed the photon theory?

A

einstein

93
Q

what is refraction?

A

the bending of a wave due to a change in speed

94
Q

what is reflection?

A

the return of a wave from a surface

95
Q

what is polarization?

A

confining a wave to vibrate in one direction

96
Q

what is diffraction?

A

the bending of a wave as it passes by a boundary or object

97
Q

what is a normal line?

A

a line drawn perpendicular to the surface of the mirror or boundary where refraction of reflection occurs

98
Q

what happens as a light ray goes from a less dense to a more dense substance?

A

the light bends toward the normal line

99
Q

what does the amount of bending in a refraction depend on?

A

the density if the substance

100
Q

what is the angle of incidence?

A

the angle between an incoming light ray and the normal line

101
Q

what is the angle of reflection?

A

the angle between the reflected light ray and the normal line

102
Q

what is unpolarized light?

A

electromagnetic waves that are vibrating in many different planes

103
Q

what is polarized light?

A

filtered light that only vibrates in one plane

104
Q

what does the amount of bending in diffraction depend on?

A

the size of the opening

105
Q

what does a wide gap create?

A

high resolution image

106
Q

what does a narrow gap create?

A

low resolution image

107
Q

who created the refracting telescope?

A

galileo

108
Q

what type of lenses does a refracting telescope use?

A

convex and concave lenses

109
Q

who created the reflecting telescope?

A

newton

110
Q

what type of lenses does a reflecting telescope use?

A

a convex lens, plane and concave mirror

111
Q

what are radiation telescopes?

A

they use satellites to collect data on all types of EMR, don’t work well with high frequency

112
Q

what forms EMR?

A

thermonuclear fusion

113
Q

what is thermonuclear fusion?

A

when two hydrogen atoms combine to form a helium atom and one neutron (H + H –> He + n)

114
Q

why are stars so hot?

A

because thermonuclear fusion releases so much energy

115
Q

what forms gamma rays?

A

the nuclear fusion reaction

116
Q

where do gamma rays come from?

A

the sun’s core

117
Q

how does a spectroscope work?

A

the light from stars is passed through a prism or diffraction grating and separated into its component wavelengths

118
Q

what are the 3 types of spectra?

A
  1. continuous spectrum
  2. dark line/absorption line spectrum
  3. bright line/emission line spectrum
119
Q

what is a continuous spectrum?

A

all colours of the spectrum are emitted

120
Q

what is dark line/absorption line spectrum?

A

spectrum with a series of dark lines, each gas has its own unique absorption spectrum which can be used to identify gases

121
Q

what is bright line/emission line spectrum?

A

a black background with coloured bands of light, produced when energy is passed through a gas, the gas absorbs specific wavelengths of energy and that energy is emitted as photons of light at specific wavelengths which gives them specific color

122
Q

what is the doppler effect?

A

a change in the observed frequency of a wave due to motion between the source and the observer

123
Q

when does a star collapse?

A

when the fuel is used up and the energy flow from the energy flow from the star’s core stops

124
Q

what is the evolution of a low mass star?

A

nebulae, low mass star, red giant, planetary nebula, white dwarf

125
Q

what is the evolution of an intermediate mass star?

A

nebulae, intermediate mass star, supergiant, supernova, neutron star

126
Q

what is the evolution of a high mass star?

A

nebulae, high mass star, supergiant, star collapse supernova, blackhole

Science 30 (5 decks)

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