AQA PHYA1 JAN13

Question 1

Name the constituent of an atom which has zero charge

1 mark

Answer 1

Neutron

Question 2

Name the constituent of an atom which has the largest specific charge

1 mark

Answer 2

Electron

Question 3

Nam the constituent of an atom which when removed leaves a different isotope of the element

1 mark

Answer 3

Neutron

Question 4

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

Answer 4

Pair production

Question 5

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

Answer 5

Kinetic energy of electron and positron

Question 6

Describe what is likely to happen to the positron shortly after its creation.

2 marks

Answer 6

It will meet an electron and annihilate converting into two or more photons or gamma rays

Question 7

State how many quarks there are in a Baryon

1 mark

Answer 7

Three

Question 8

Hadrons fall into two groups, baryons being one of them. State the name that is given to the other group of hadrons.

1 mark

Answer 8

Mesons

Question 9

Give two properties of hadrons that distinguish them from leptons.

2 marks

Answer 9

Experience the strong interaction

Made up of quarks or not fundamental

Eventually decay to a proton

Question 10

The forces between particles can be explained in terms of exchange particles. Complete the table.

Interaction-exchange particle
Electromagnetic-?
Weak-?

Answer 10

(Virtual) photon

W+

Question 11

Interaction weak has a exchange particle

Answer 11

W+

Or

W-

Or

Z to power 0

Question 12

Explain why, when electron capture occurs, a neutron rather than an antineutrino is produced.

1 mark

Answer 12

Lepton number must be conserved

+1 on lhs must be +1 on rhs

Question 13

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.

Answer 13

Absorbs enough energy (from the incident) electron (by collision)

Exact energy/10.1 (eV)needed to make the transition/ move up to level 2

Question 14

Calculate the frequency of the photon

Answer 14

Use of E2 - E1 =hf

Question 15

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

Answer 15

Electrons return to lower levels by different routes/cascade/ not straight to ground state.

Question 16

State and explain how many possible frequencies could be produced.

2 marks

Answer 16

3

N=3 to n=1

Question 17

An experiment can be performed to determine whether a particular component is an ohmic conductor.

State what is meant by an ohmic conductor.

Answer 17

A component with constant resistance where v is proportional to I

Question 18

Draw a suitable diagram for a such an experiment

determine ohmic or not

Answer 18

A—variable resistor—v in parallel—battery

Question 19

Describe experiment: measurements? How to use these? How to reach a conclusion?

6 marks

Answer 19

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.

Question 20

State a principle property of a superconductor.

Answer 20

Has 0 resistance at and below a critical temperature.

A material with zero resistivity

Question 21

State what is meant by critical temperature.

Answer 21

Material becomes super conducting at/ below critical temperature

Question 22

Give one use of a superconductor.

Answer 22

In particle accelerators

Question 23

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.

Answer 23

No change as constant pd across resistors/ parallel branches

Question 24

With internal resistance that is now not negligible

Answer 24

Lamp would be less bright as energy is wasted in internal resistance

Current lower due to greater resistance