A level physics Exam
With answers
What is the actual charge, relative charge, actual mass and relative mass of the proton, neutron
and electron? - answer-Proton:
-Actual charge: +1.60 x 10^-19 C
-Relative charge: +1
-Actual mass: 1.673 x 10^-27 Kg
-Relative mass: 1
Neuton:
-Actual charge: 0 C
-Relative charge: 0
-Actual mass: 1.675 x 10^-27 Kg
-Relative mass: 1
Proton:
-Actual charge: -1.60 x 10^-19 C
-Relative charge: -1
-Actual mass: 9.11 x 10^-31 Kg
-Relative mass: 0.0005
What are isotopes?
Why do different isotopes of the same element have the same chemical properties? - answer-
Atoms with the same number of protons but a different number of neutrons in their nuclei.
Their electronic configurations are the same.
How can scientists discern the age of dead organic matter via carbon-14? - answer-1. All living
things contain the same percentage of carbon-14 taken in from the atmosphere.
2. After they die, carbon-14 percentage falls as it decays to more stable elements.
3. Scientists can calculate the approximate age of the matter by using isotopic data to calculate
the percentage of carbon-14 left.
What is the equation for specific charge? - answer-Specific charge/C kg^-1 =
(Charge/C)/(Mass/kg)
What does the strong force do?
Why must it exist?
What is the range of the strong force like?
,Draw a graph to demonstrate this, including a curve for the electrostatic forces in the nucleus. -
answer-The strong force holds nucleons together.
The electrostatic forces of repulsion in the nucleus massively exceeds the gravitational forces of
attraction; if those were the only forces, the nucleus would fly apart.
Strong force has a very short range - it can only hold nucleons together when they're separated
by a few femtometres. Attraction falls to zero quickly beyond 3 fm.The strong force must be
repulsive before 0.5fm, otherwise it'd crush the nucleus to a point.
Refer to big sheets
To what sorts of nuclei does alpha emission occur? Why?
Write an equation for the alpha decay of the uranium-238 nucleus.
What happens to A and Z when an alpha particle is emitted?
What do alpha particles' tracks look like in a cloud chamber? Why? - answer-Very big nuclei,
like uranium and radium - the nuclei of these atoms can be too massive for the strong nuclear
force to hold them together.
Refer to big sheets
Proton number decreases by 2, nucleon number by 4.
Short lines - they have a very short range, only a few cm in air.
In what sorts of nuclei does B- emission occur?
Write an equation for the B- emission of the rhenium-187 nucleus.
What happens to A and Z when a B- particle is emitted? - answer-Neutron-rich nuclei, as it
converts neutrons to protons.
Refer to big sheets
Proton number increases by 1, nucleon number stays the same.
In what sorts of nuclei does B+ emission occur?
Write an equation for the B+ emission of the nickel-59 nucleus.
,What happens to A and Z when a B- particle is emitted? - answer-Proton-rich nuclei, as it
converts protons to neutrons.
Refer to big sheets
Proton number decreases by 1, nucleon number stays the same.
Why were neutrinos hypothesised?
Why weren't neutrinos detected originally?
What must a neutrino's charge be and why? - answer-Observations showed that energy of
known particles after beta decay was less than before, which didn't abide by the law of energy
conservation. There must have been a particle that carried away the missing energy and
momentum.
Neutrinos weren't initially detected due to having almost zero mass.
A neutrino must have zero charge, or else charge wouldn't be conserved in beta decay.
What is the equation for a photon's energy?
What is Planck's constant's value?
Rank the different types of EM radiation, so that frequency increases down the list; give the
approximate frequency range for each, in Hertz. - answer-E = hf = hc/λ
h = 6.63 x 10^-34Js
Radio waves: < 3 × 10^9
Microwaves: 3 × 10^9 - 3 × 10^12
Infrared radiation: 3 × 10^12 - 4.3 × 10^19
Visible light: 4.3 × 10^14 - 7.5 × 10^14
Ultraviolet: 7.5 × 10^14 - 3 × 10^17
X-rays: 3 × 10^17 - 3 × 10^19
Gamma rays: > 3 × 10^19
What similarities and differences do corresponding particles and antiparticles have?
What is the electron's antiparticle?
Neutrino properties? - answer-Similarities:
-Same mass
-Same rest energy
, Differences:
-Opposite charge
Positron
Almost zero mass, zero charge, they're leptons.
What is the idea of mass-energy equivalence? What happens upon conversion?
How does this occur when 2 protons are fired at each other at high speeds? - answer-You can
convert energy into mass, and when this happens, equal amounts of matter and antimatter
form.
Fire two protons at each other at high speeds and you get lots of energy at the point of contact,
which can be converted to more particles. Therefore, 3 protons (1 from energy) and 1 antiproton
(from energy) can emerge.
What is pair production?
Why is it only really gamma photons that undergo pair production?
Why is it generally electron-positron pairs that are produced in pair production compared to
other particle-antiparticle pairs?
Draw a diagram to display the pair production of an electron and positron in a magnetic field -
why do they travel in different directions - answer-Pair production is when energy (in the form of
a photon) is converted to matter (in the form of a particle and its corresponding antiparticle).
It's only really gamma photons that have a higher enough frequency and energy to produce
enough mass.
This pair has a relatively low mass compared to other particle-antiparticle pairs?
Refer to big sheets
Due to having opposite charges
What equations show the minimum energy of the photon needed for pair production to occur -
label terms when necessary. - answer-E min = hf min = 2E0
E0 = rest energy of each particle/antiparticle produced.
What occurs in annihilation?
Why are 2 photons produced?
With answers
What is the actual charge, relative charge, actual mass and relative mass of the proton, neutron
and electron? - answer-Proton:
-Actual charge: +1.60 x 10^-19 C
-Relative charge: +1
-Actual mass: 1.673 x 10^-27 Kg
-Relative mass: 1
Neuton:
-Actual charge: 0 C
-Relative charge: 0
-Actual mass: 1.675 x 10^-27 Kg
-Relative mass: 1
Proton:
-Actual charge: -1.60 x 10^-19 C
-Relative charge: -1
-Actual mass: 9.11 x 10^-31 Kg
-Relative mass: 0.0005
What are isotopes?
Why do different isotopes of the same element have the same chemical properties? - answer-
Atoms with the same number of protons but a different number of neutrons in their nuclei.
Their electronic configurations are the same.
How can scientists discern the age of dead organic matter via carbon-14? - answer-1. All living
things contain the same percentage of carbon-14 taken in from the atmosphere.
2. After they die, carbon-14 percentage falls as it decays to more stable elements.
3. Scientists can calculate the approximate age of the matter by using isotopic data to calculate
the percentage of carbon-14 left.
What is the equation for specific charge? - answer-Specific charge/C kg^-1 =
(Charge/C)/(Mass/kg)
What does the strong force do?
Why must it exist?
What is the range of the strong force like?
,Draw a graph to demonstrate this, including a curve for the electrostatic forces in the nucleus. -
answer-The strong force holds nucleons together.
The electrostatic forces of repulsion in the nucleus massively exceeds the gravitational forces of
attraction; if those were the only forces, the nucleus would fly apart.
Strong force has a very short range - it can only hold nucleons together when they're separated
by a few femtometres. Attraction falls to zero quickly beyond 3 fm.The strong force must be
repulsive before 0.5fm, otherwise it'd crush the nucleus to a point.
Refer to big sheets
To what sorts of nuclei does alpha emission occur? Why?
Write an equation for the alpha decay of the uranium-238 nucleus.
What happens to A and Z when an alpha particle is emitted?
What do alpha particles' tracks look like in a cloud chamber? Why? - answer-Very big nuclei,
like uranium and radium - the nuclei of these atoms can be too massive for the strong nuclear
force to hold them together.
Refer to big sheets
Proton number decreases by 2, nucleon number by 4.
Short lines - they have a very short range, only a few cm in air.
In what sorts of nuclei does B- emission occur?
Write an equation for the B- emission of the rhenium-187 nucleus.
What happens to A and Z when a B- particle is emitted? - answer-Neutron-rich nuclei, as it
converts neutrons to protons.
Refer to big sheets
Proton number increases by 1, nucleon number stays the same.
In what sorts of nuclei does B+ emission occur?
Write an equation for the B+ emission of the nickel-59 nucleus.
,What happens to A and Z when a B- particle is emitted? - answer-Proton-rich nuclei, as it
converts protons to neutrons.
Refer to big sheets
Proton number decreases by 1, nucleon number stays the same.
Why were neutrinos hypothesised?
Why weren't neutrinos detected originally?
What must a neutrino's charge be and why? - answer-Observations showed that energy of
known particles after beta decay was less than before, which didn't abide by the law of energy
conservation. There must have been a particle that carried away the missing energy and
momentum.
Neutrinos weren't initially detected due to having almost zero mass.
A neutrino must have zero charge, or else charge wouldn't be conserved in beta decay.
What is the equation for a photon's energy?
What is Planck's constant's value?
Rank the different types of EM radiation, so that frequency increases down the list; give the
approximate frequency range for each, in Hertz. - answer-E = hf = hc/λ
h = 6.63 x 10^-34Js
Radio waves: < 3 × 10^9
Microwaves: 3 × 10^9 - 3 × 10^12
Infrared radiation: 3 × 10^12 - 4.3 × 10^19
Visible light: 4.3 × 10^14 - 7.5 × 10^14
Ultraviolet: 7.5 × 10^14 - 3 × 10^17
X-rays: 3 × 10^17 - 3 × 10^19
Gamma rays: > 3 × 10^19
What similarities and differences do corresponding particles and antiparticles have?
What is the electron's antiparticle?
Neutrino properties? - answer-Similarities:
-Same mass
-Same rest energy
, Differences:
-Opposite charge
Positron
Almost zero mass, zero charge, they're leptons.
What is the idea of mass-energy equivalence? What happens upon conversion?
How does this occur when 2 protons are fired at each other at high speeds? - answer-You can
convert energy into mass, and when this happens, equal amounts of matter and antimatter
form.
Fire two protons at each other at high speeds and you get lots of energy at the point of contact,
which can be converted to more particles. Therefore, 3 protons (1 from energy) and 1 antiproton
(from energy) can emerge.
What is pair production?
Why is it only really gamma photons that undergo pair production?
Why is it generally electron-positron pairs that are produced in pair production compared to
other particle-antiparticle pairs?
Draw a diagram to display the pair production of an electron and positron in a magnetic field -
why do they travel in different directions - answer-Pair production is when energy (in the form of
a photon) is converted to matter (in the form of a particle and its corresponding antiparticle).
It's only really gamma photons that have a higher enough frequency and energy to produce
enough mass.
This pair has a relatively low mass compared to other particle-antiparticle pairs?
Refer to big sheets
Due to having opposite charges
What equations show the minimum energy of the photon needed for pair production to occur -
label terms when necessary. - answer-E min = hf min = 2E0
E0 = rest energy of each particle/antiparticle produced.
What occurs in annihilation?
Why are 2 photons produced?
