AQA PHYA1 JAN13 Flashcards
Name the constituent of an atom which has zero charge
1 mark
Neutron
Name the constituent of an atom which has the largest specific charge
1 mark
Electron
Nam the constituent of an atom which when removed leaves a different isotope of the element
1 mark
Neutron
Under certain circumstances it is possible for a photon to be converted into an electron and a positron. State what process this is called.
1 mark
Pair production
A photon of slightly higher energy than that calculated in part b is converted into an electron and a positron. State what happens to the excess energy.
1 mark
Kinetic energy of electron and positron
Describe what is likely to happen to the positron shortly after its creation.
2 marks
It will meet an electron and annihilate converting into two or more photons or gamma rays
State how many quarks there are in a Baryon
1 mark
Three
Hadrons fall into two groups, baryons being one of them. State the name that is given to the other group of hadrons.
1 mark
Mesons
Give two properties of hadrons that distinguish them from leptons.
2 marks
Experience the strong interaction
Made up of quarks or not fundamental
Eventually decay to a proton
The forces between particles can be explained in terms of exchange particles. Complete the table.
Interaction-exchange particle
Electromagnetic-?
Weak-?
(Virtual) photon
W+
Interaction weak has a exchange particle
W+
Or
W-
Or
Z to power 0
Explain why, when electron capture occurs, a neutron rather than an antineutrino is produced.
1 mark
Lepton number must be conserved
+1 on lhs must be +1 on rhs
An electron is incident on a Hydrogen atom. As a result an electron in the ground state of the hydrogen atom is excited to the n=2 energy level. The atom then emits a photon of a characteristic frequency.
Explain why the electron in the ground state becomes excited to the n=2 energy level.
2 marks.
Absorbs enough energy (from the incident) electron (by collision)
Exact energy/10.1 (eV)needed to make the transition/ move up to level 2
Calculate the frequency of the photon
Use of E2 - E1 =hf
When electrons in the ground state of hydrogen atoms are excited to the n=3 energy level, photons of more than one frequency are subsequently released.
Explain why different frequencies are possible.
1 mark
Electrons return to lower levels by different routes/cascade/ not straight to ground state.
State and explain how many possible frequencies could be produced.
2 marks
3
N=3 to n=1
An experiment can be performed to determine whether a particular component is an ohmic conductor.
State what is meant by an ohmic conductor.
A component with constant resistance where v is proportional to I
Draw a suitable diagram for a such an experiment
determine ohmic or not
A—variable resistor—v in parallel—battery
Describe experiment: measurements? How to use these? How to reach a conclusion?
6 marks
Have a means of varying the current. Set current to different values and measure pd. use a wide range. To vary current - variable resistor is sensible. Plot graph of pd against current. Relate a constant gradient to be a constant resistance. Draw line if best fit and state r constant. Straight line indicates an ohmic conductor.
State a principle property of a superconductor.
Has 0 resistance at and below a critical temperature.
A material with zero resistivity
State what is meant by critical temperature.
Material becomes super conducting at/ below critical temperature
Give one use of a superconductor.
In particle accelerators
The thermistor is heated so that it’s resistance decreases. State and explain the effect this has on the voltmeter reading in the following positions.
No change as constant pd across resistors/ parallel branches
With internal resistance that is now not negligible
Lamp would be less bright as energy is wasted in internal resistance
Current lower due to greater resistance
