Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

physics > spec > Flashcards

spec Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

what is the difference between AC and DC

A

AC is constantly changing magnitude and direction. AC is how mains electricity is produced from turbines.

DC is constant and is produced from a battery and used in some sensitive components like in computing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

watt happens when you increase the voltage

A

As voltage increases the current also increases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what happens when you have more components in a circuit

A

In general, the more components in a circuit, the lower the current.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what would the graph look like with an ohmic resistor, a filament lamp and a diode

A

a straight like, an “S’, a horisontal line and up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what happens when you increase the resistance in a circuit

A

Since V = IR, as you increase the resistance in a circuit, the current will decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

electric current in solid metallic conductors is…

A

a flow of negatively charged electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

to calculate total voltage in a series circuit

A

V1 +V2 +V3…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

to calculate total resistance in a series circuit

A

R1 + R2 + R3…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

total current in a series circuit

A

I1 = I2 = I3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wavefront

A

Created by overlapping lots of different waves. The wavefront is the front of the wave, or the same point on each wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Amplitude

A

The maximum displacement of particles from their equilibrium position.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Wavelength

A

The distance between a particular point on one cycle of the wave and the same point on the next cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Frequency

A

The number of waves passing a particular point per second. Is measured in Hertz (Hz).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Time Period

A

The time it takes for one complete wave to pass a particular point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

electromagnetic spectrum

A

radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray radiations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how does the speed differ for the waves in the electromagnetic spectrum in free space

A

all these waves travel at the same speed in free space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

electromagnetic spectrum from biggest wave length to smallest wave length

A

radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray radiations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

electromagnetic spectrum from biggest frequency to smallest frequency

A

gamma ray radiations, x-ray, ultraviolet, visible, infrared, microwave, radio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

visible light, from lowest to highest frequency

A

Red, orange, yellow, green, blue, indigo, violet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

use of radio waves

A

broadcasting and communications

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

use of microwaves

A

cooking and satellite transmissions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

use of infrared

A

heaters and night vision equipment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

use of visible light

A

optical fibres and photography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

use of ultraviolet

A

fluorescent lamps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

use of x rays

A

observing the internal structure of objects and materials, including for medical applications

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

use of gamma rays

A

sterilising food and medical equipment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

effects of microwaves

A

internal heating of body tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

effects of infrared

A

skin burns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

effects of ultraviolet

A

damage to surface cells and blindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

effects of gamma rays

A

cancer, mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

protection from UV

A
  • sun glasses
  • sun cream
  • stay in shade
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

protection from gamma rays

A

Wear led clothing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

investigate the refraction of light, using rectangular blocks / semicircular blocks / triangular prisms

A
  • draw outline of block
  • Draw the normal
  • Draw a line at 30 degrees to the normal, and shine a ray of light on the line
  • Draw a line where the light emerges on the other side (emergent ray) and connect the two lines
  • Measure the angle of the emergent ray
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what happens to refraction as a medium becomes more dense

A

light bends towards the normal, because the light rays in the denser medium move slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

total internal refraction in optical fibres

A

You send the light in at an angle that is more than the critical angle of the internal core material, so it totally internally reflects.

Optical fibres are not bent much to ensure that it always hits the core at more than the critical angle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

how is total internal reflection useful in optical fibres

A

Optical fibres are used to transmit information. Total internal reflection is very useful in optical fibres as no information is lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what are optical fibres made from

A

glass , plastic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what stops total internal reflection in optical fibres

A

This total internal reflection will only not occur if the optical fibre is bent too sharply.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

total internal refraction in prisms (e.g. periscopes)

A

white light is shone through the triangular prisms. White light is in the very middle of the EM spectrum, so is a combination of all the waves, from red to violet. Therefore, when shone into a prism, each part refracts different amounts, so they separate into their colour when they leave the prism.

40
Q

explain what is meant by critical angle

A
  • The angle of incidence which produces an angle of refraction of 90
  • When the angle of incidence is greater than the critical angle, total internal reflection occurs
  • This effect only occurs at a boundary from a high refractive index material to a low refractive index material.
41
Q

energy stores

A

chemical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic, nuclear

42
Q

energy transfers

A

mechanically, electrically, by heating, by radiation (light and sound)

43
Q

the principle of conservation of energy

A

In any process energy is never created or destroyed. (It is just transferred from one store to another.)

44
Q

what is work done equal to

A

energy transfered

45
Q

relationship between GPE and kinetic energy for a falling object

A

Because energy is conserved,
the decrease in GPE = increase in KE, for a falling object if no energy is lost to the surroundings

46
Q

what is power?

A

rate of work done.

p = E/t

47
Q

pressure in liquids and gas

A

Pressure in gases and liquids (at rest) act equally in all directions.

48
Q

what happens when the same force is applied over a larger area

A

If the same force is applied over a larger area, there will be a lower pressure

49
Q

what happens the the thermal and kinetic energy of particles at absolute zero

A

At absolute zero the particles have no thermal energy or kinetic energy, so they cannot exert a force.

50
Q

absolute zero

A

0 Kelvin = -273˚C

51
Q

rhyme to remember how to convert kelvin to celcius

A

K is equal to degrees C plus 273

52
Q

relationship between kelvin temperature and kinetic energy

A

The Kelvin temperature of a gas is proportional to the average kinetic energy of its molecules.

53
Q

feild line practical

A
  • draw around bar magnet
  • Place a compass at one pole
  • Draw a ‘dot’ to show there the compass is pointing,
  • Move the compass so the opposite end of the needle is pointing to the dot,
  • Repeat steps 3 and 4 until to reach the other pole of the magnet.
  • Do this procedure at least 5 times from different points on the pole of the magnet.
  • Join up your dots to create the field line plots
54
Q

what is a uniform magnetic feild?

A

A uniform magnetic field is comprised of straight, parallel lines which are evenly spaced. Between two opposite charges on flat magnets, a uniform magnetic field is formed.

55
Q

how to make a uniform magnetic field with permanent bar magnets

A

If you put two opposite poles close to each other, they will attract and make a uniform magnetic field.
The closer together, the stronger the magnetic field.

56
Q

what happens when an electric current flows in a conductor

A

produces a magnetic field around it

57
Q

how does a d.c electric motor work

A
  • Current flows in the wire/coil.
  • This creates a magnetic field around the wire/coil.
  • This magnetic field interacts with the field from the permanent magnet.
  • This produces a force on the wire/coil which moves the wire/coil.
  • The split-ring commutator changes the direction of the current every half turn as it spins. This reverses the direction of the forces, allowing the coil to continue spinning.
58
Q

how does a loudspeaker work?

A
  • An alternating current from the source passes though the coils in the speaker.
  • This current is constantly changing direction and magnitude
  • This current creates a magnetic field around the coil
  • This field interacts with the magnetic field from the permanent magnets
  • Creating a constantly changing force on the coil.
  • This causes the coil to vibrate in and out as the direction of the force changes, moving the cone
  • The cone causes vibrations which we hear as sound waves.
59
Q

atomic number

A

the number of protons in an atom

60
Q

mass number

A

protons + neutrons

61
Q

when do we mean when we say that a material is “radioactive”

A

it consists of unstable isotopes that can decay

62
Q

what chemical symbol do we normally represent alpha (α) radiation with

A

He
(helium, as it has 2 protons and 2 neutrons)

63
Q

charge of alpha (α) radiation

A

2+
(as it doesn’t have any electrons)

64
Q

what can alpha particles be absorbed by?

A

a single sheet of paper (their particles are fairly large so they don’t penetrate far)

65
Q

how ionising are alpha (α) particles?

A

strongly ionising (meaning they can easily knock electrons off of any atoms they collide with)

66
Q

charge of a beta particle

A

-1 (as it is an electron)

67
Q

what can beta particles be absorbed by?

A

5mm of aluminium (they penetrate moderatley far)

68
Q

how ionising are beta particles?

A

moderatley ionising

69
Q

if gamma rays are not particles, then what are they?

A

waves of electromagnetic radiation

70
Q

how ionising are gamma rays?

A

weakly ionising (as they have no mass or charge and so pass through materials)

71
Q

what can gamma rays be absorbed by?

A

thick sheets of lead or multiple layers of concrete (as they penetrate really far)

72
Q

what is ionisation?

A

when an atom loses or gains an electron, causing it to become an ion (an atom which is positively or negatively charged).

73
Q

explain how alpha beta and gamma rays are made

A
  • all are emitted from unstable nuclei (in an attempt to make them more stable),known as radioactive decay.
  • It is spontaneous and random, there is no (current) way of detecting when an unstable nucleus will decay and there is no way of speeding up/slowing down the process as it is completely unaffected by physical conditions (such as temperature or pH) or by and sort of chemical reactions/bondings.
74
Q

what is background radiation

A

the radiation that exists around us all the time

75
Q

background radiation from rock

A

Radon gas

76
Q

background radiation from space

A

cosmic rays

77
Q

background radiation from biological material

A

Carbon-14

78
Q

background radiation from food and drink

A

radioactive material

79
Q

what is meant by half life

A

half-life is the time taken for half of the radioactive atoms now present to decay.

80
Q

uses of radioactivity in medical tracer

A

– Radioactive tracer put in body (swallowed/injected)

– Detector put around body

– Computer generates an image

81
Q

uses of radioactivity in sterilisation

A
  • Medical equipment irradiated
  • Kills all living matter on tools (e.g. bacteria)
82
Q

uses of radiation in radiotherapy

A

High doses of radiation are directed at cancer cells
Cancer cells are killed

83
Q

whats the difference between contamination and irradiation

A
  • Contamination:
    Occurs when material that contains radioactive atoms is deposited on materials, skin, clothing, or any place where it is not desired.
  • Irradiation:
    The process by which an object is exposed to radiation.
84
Q

the dangers of ionising radiations

A
  • radiation can cause mutations in living organisms
  • that radiation can damage cells and tissue
85
Q

why is the disposal of radioactive waste dangerous?

A

it emits radioactive particles, which if not properly managed can be a risk to human health and the environment.

86
Q

what is done to make disposal of radioactive waste more safe?

A

Radioactive waste with a long half-life is buried underground to prevent it from being released into the environment

87
Q

nuclear reactions, including fission, fusion and radioactive decay can be a source of

A

energy

88
Q

nuclear fission

A
  • A “slow” neutron is absorbed by a uranium-235 nucleus.
  • making the nucleus unstable
  • splits apart to form two smaller daughter nuclei, and a few neutrons
  • If more than one neutron from each fission causes fission in surrounding nuclei, the reaction escalates.
  • This is called chain reaction.
  • This involves sudden release of enormous heat energy and radiation.
89
Q

what is sheilding?

A

Reactor vessel is made of steel and surrounded by a concrete layer about 5 meters thick.
This prevents any radiation escaping, even neutrons.

90
Q

what is the scource of energy for our sun and all stars

A

nuclear fusion

91
Q

in the sun, ____ undergoes nuclear fusion to create ____

A

hydrogen, helium

92
Q

why does the moon have a weaker gravidational feild strength

A

The Moon has less mass than the Earth, so its gravitational field is much weaker – approx 1/6th of the Earth’s.

93
Q

why does the moon orbit the earth?

A

According to Newton, there is an attractive gravitational force between any two objects– pulling them together

Moons and artificial satellites are attracted to their planets, and so are pulled towards them.

This gravitational force keeps them moving in curved paths called orbits. The Moon does not crash into the Earth, and the planets do not crash into the Sun because they are moving.

94
Q

differences between the orbit of the moon and the planets and the comets

A

Moons: They orbit planets, have an elliptical orbit.

Planets: They orbit stars, have an elliptical orbit.

Comets: They orbit stars, have a highly elliptical orbit.

95
Q

hottest to coolest colours

A

blue - white - yellow - orange - red

96
Q

evolution of stars of similar mass to the Sun stages:

A
  • nebula
  • star (main sequence)
  • red giant
  • white dwarf.

physics (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions