AQA Alevel Physics Paper 1

All year 1 content overview

What are the SI base units?

Kilogram, metres, seconds, amperes, kelvin, mole

what is the value of 1eV

1.6×10^-19 C = 1.6×10^-19 J

what are random errors ?

Unpredictable fluctuations in data or instrument readings

How to reduce random errors?

Repeat multiple times and take averages

what is a systematic error?

An error whihc stems from fault of the equipment

How to reduce systematic errors?

calibrate instruments or use different ones

what is a zero error?

When the instrument has not being set to zero before reading takes place / experiment takes place

what does precise measurements mean?

little spread about the mean value

what is accuracy?

a reading is accurate if it is close to the true value

What is repeatability?

if the experiment is repeated using same method and equipment, and the same data is acquired

what is reproducibility?

if experiment is repeated with different people, equipment, or methods, and the same data is acquired

What s resolution?

The smallest change in a reading ( eg the scale of a ruler, etc )

what is an absolute uncertainty ?

the uncertainty is given as a fixed amount

what is fractional uncertainty?

uncertainty is given as a fraction of the measurement

what is percentage uncertainty?

given as a percentage of the measurement

how to find uncertainty of the reading?

+ half the smallest division

how to find uncertainty of the measurement?

+at least 1 smallest divison

what is the uncertainty in repeated data ?

+half the range

what is the uncertainty for digi reading?

+the siginificant figure digit

how to add/subtract data

add together the absolute uncertainties

how to multiply/divide data

add the percentage or fractional uncertainties

how to raise data to the power

multiply percentage by the power

what is an atom made up of

• positively charged nucleus with protons and neutrons

• orbiting negatively charged electrons

what is specific charge

the charge per unit mass of a substance

what is the nucleon number

• top number

• both protons and neutrons added together

what is the atomic number

the total number of protons

what is an isotope

nuclei of the same element which have the same number of protons (atomic number)but a different number of netrons (atomic mass)

what are the four fundamental forces

gravity, electrostatic, strong nuclear force, weak nuclear force

what is the electrostatic force

the repulsive force between two positively charged protons

what is the gravitational force

a force that acts on objects with a mass

what is the strong nuclear force

opposes the electrostatic force

• holds the nucleus together

• acts between particles known as quarks

when is the strong nuclear force applicable?

• below 0.5fm, repulsive

• between 0.5fm and 3-4fm attractive

• negligible past 3-4 fm

what is alpha decay

unstbale nuclei emits alpha particle(helium nucleus) and decays into different nucleus

• atomic mass decreases by 4

• atomic number decreases by 2

what is beta - decay

a fast moving high energy electron which is emitted from the nucleus

• neutron turns into proton, emitting electron and antineutrino in the process

• atomic mass stays the same

• atomic number increases by 1

what is beta + decay

high energy positron emitted from nucleus

• proton turns to neutron, emitting positron and neutrino in process

• atomic mass stays the same

• atomic number decreases by 1

what is the purpose of a neutrino/antinuetrino

balances the decay to ensure conservation of charge, real particles is conserved

what is antimatter

the ideal that all particles have an opposing identicle antiparticle with an opposing charge

what are the properties of antiparticles

• opposite charges

• same rest mass

• same rest energy

what is a photon?

a packet of EM waves

how to calculate photon energy

E = hf

what is annihilation?

when particle and corresponding antiparticle meet, they will annhilate

• pair will destroy, emits two gamma ray photons (each half the energy) in opposite directions (conservation of momentum)

what is pair production?

the creation of a particle-antiparticle pair when a high energy photon randomly converts its energy to mass

what is a hadron?

a group of subatomic particles made up of quarks

what are the two types of hadrons ?

baryons ( qqq or qqq) and mesons (qq)

what is baryon number?

the number of baryons in an interaction

• baryon number conserved in all interactions

what is a pion?

the lightest type of meson

what is the stron nuclear force exchange particle?

the pion

what do gluons do?

bind together the quarks

what is a kaon?

a heavier and unstable meson which will decay into a pion

what quarks do all kaons have?

strange quarks

how does a kaon decay

the weak nuclear force

what is a lepton?

A fundamental particle ( cannot bebroken down further )

how to leptons interact

through gravitational, electromagnetic, or weak nuclear

what is lepton number

the number of leptons in an interaction. must be conserved

how does a muon decay?

through the weak interaction - exchange of a w- boson

what does the gravitaional force effect?

any particles with a mass

what does the electromagnetic force effect?

any particles with a charge

what does the weak nuclear force effect?

all particles

what does the weak nuclear force effect?

only hadrons

what is an exchange particle ?

a virtual particle which carries the fundamental force between the particles

when does the electromagnetic force occur?

occurs when two charged particles interact with each other

what is the exchange particle for electromagnetic

a photon

what is the exchange particle for the strong nuclear force

pions (between nuleons) and gluons between quarks

what is responsible for decay

the weak nuclear force

what is electron capture?

an electron is absorbed by a proton in the nucleus, emitting a neutron and a neutrino in the process ( w+ boson)

what is apparent magnitude?

the perceived brightness of star viewed from earth

what magnitude represents brightest stars

1.0

what magnitude represents dimmest stars

6.0

what is the scale of apparent magnitude?

hipparcos scale is logarithmic

how to compare the brightness of two objects

I_A / I_B = 2.51(^m_B-m_A)

what is the relationship between apparent magnitude and brightness?

order of magnitude of apparent brightness is an increase of or decrease in brightness by factor of 2.51

the more negative the apparent magnitude

the brighter the object appears

the more positive the apparent magnitude

the fainter the object appears

what is luminosity?

the total power output of radiation emitted by a star

what is brightness of the star

the intensity of radiation received on earth

difference between brightness and luminosity ?

luminosity is total power output of star, brightness is the power as measured on earth

what is inverse square law?

when light is twice as far away, area is spread over 4 times area, so intensity is 4 times smaller

what is AU ( astronomical unit)

the mean distance from the centre of the earth to the centre of the sun

what is a lightyear?

the distance travelled by light in one year

what is 1 parsec

3.1×10⁶m

what is absolute magnitude?

the apparent magnitude it would have if it was observed from a distance of 10 parsecs away from earth

what is the distance between the apparent magnitude and absolute magnitude?

the distance modulus

what is a black body radiator

absorbs and emits all wavelengths

what does the intensity-wavelength graph show

how the thermodynamic temperature links to the peak wavelength

what colour are cooler objects

red and yellows

what colour are hotter objects

white or blue

What is stephans law?

the total energy emitted for a black body per unit area per second is proportional to the fourth power of the absolute temperature of the object

how is stephans law calculated

P =