Physics Revision Module 4

How to Use these Notes

These revision notes are in the order of the syllabus, whereas the order of the topics on the website reflects the order in the scheme of work that I use with my A2 students. 

Each section is a subsection of the syllabus.  You may find it helpful to cover one subsection at a time.

Use the BACK button in your browser to get back to these notes after following a hyperlink.

Theme 1 Oscillations and Waves

1. Simple harmonic motion: graphical and analytical treatments

In the exam you are expected to know:

  • Characteristic features of simple harmonic motion

  • Exchange of potential and kinetic energy in oscillatory motion

  • Understanding and use of the following equations

 

 

 

  • Graphical representations linking displacement, velocity, acceleration , time and energy

  • Velocity as gradient of displacement/time graph

  • Simple pendulum and mass-spring as examples and use of the equations

 

 

 

  • Candidates should have experience of the use of data-logging techniques in analysing mechanical and oscillatory systems.

 

Review the Topic 3 Notes

 

Go to http://www.s-cool.co.uk/topic_principles.asp?loc=pr&topic_id=9&subject_id=2&ebt=163&ebn=&ebs=&ebl=&elc=13

 

Then go to SHM

 

1. What is meant by period and how is it related to frequency?

 

2. What three things do you start off with then you lift the mass up?

 

3. Click on the animation.  What does it show you?

 

4. Explain what the three graphs show.

 

5.  What is the key proportionality for SHM.  Why is there a minus sign?

 

6.  What is the constant of proportionality and how can it be linked to the frequency?

 

7.  Describe the energy changes that occur in SHM.

 

Go to http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=44

 

(Note:  you have to have Macromedia Shockwave Player.  If you are at home, it's a free download.  If at college, it should be on your network, but don't download it.  You might well get into trouble with the network manager and you could be having a rather stiff interview with the Vice-Principal or Deputy Headmaster!)

 

1. Play with the mass on the spring.  Is the time period consistent with the formula:

 

2. Alter the length of the pendulum.  Is the time period T consistent with:

3. Now alter the value of the gravity field.  Which of the two systems is affected?

 

2. Free and Forced Vibration.

In the exam you are expected to know about:
  • Qualitative treatment of free and forced vibration
  • Resonance and the effects of damping
  • Examples of these effects from more than one branch of Physics e.g. production of sound in a pipe instrument or mechanical vibrations in a moving vehicle.

Read the Topic 2 Notes

Go to http://www.s-cool.co.uk/topic_principles.asp?loc=pr&topic_id=9&subject_id=2&ebt=163&ebn=&ebs=&ebl=&elc=13

Natural Frequency and Resonance are at the bottom of the page, below damped oscillations.

1.  What is an oscillation?

2.  What is meant by the natural frequency?

3.  How does resonance occur?

4.  Why do soldiers have to break step while marching over a bridge (WAIT FOR IT!)?

5. What is the effect of damping on vibrations?

 

3.Progressive waves

In the exam you are expected to know about:

  • Oscillation of the particles of the medium

  • Amplitude, frequency, wavelength, speed, phase, path difference

  • Recall and use of c = fl

Read Topic 4 Notes

Go to http://www.saburchill.com/physics/chapters2/0002.html

1.  Draw a distance-distance graph of a wave and show on it the amplitude and the wavelength.

2. Draw a distance time graph of a wave.  Show on it the period.

3.  What is meant by the term period?

4.  Why is the wave pattern shown called a sine wave?

5.  What is the wave equation?

 

4. Longitudinal waves and transverse waves

In the exam you are expected to know about:

  • Examples including sound and electromagnetic waves

  • Polarisation as evidence for the nature of transverse waves;

  • Applications, e.g. Polaroid sunglasses.

Read Topic 4 Notes

Go to http://www.physicsclassroom.com/

Go to Waves and chose Lesson 1

1.  What  is a transverse wave?

2.  What is a longitudinal wave?

 

5. Superposition of waves, stationary waves

In the exam you are expected to know about:

  • The formation of stationary waves by two waves of the same frequency travelling in opposite directions; no mathematical treatment required

  • Simple graphical representations of stationary waves, nodes and antinodes on strings and in pipes.

Read through the Topic 5 Notes

Go to http://www.saburchill.com/physics/chap04.html

1.  What are the conditions needed to form a standing wave?

2.  What is meant by the terms Nodes and Antinodes?

Go to Resonance of a String under Tension

3. Draw a diagram of a string in resonance at the fundamental frequency.  Mark on it the nodes and antinodes.

4.  What is the phase relationship of all points between the nodes?

5.  What happens if the frequency is doubled?

6.  What is the phase relationship of points either side of a node?

7.  How does the length of a resonance loop relate to the wavelength.?

Go to Resonance in Air Columns

8.  What does the resonant frequency in an air column depend on?

9. Draw a diagram of an air column at fundamental frequency.  What fraction of a wavelength is shown?

10. What happens at the next frequency at which resonance is detected?  What is the relationship of this frequency to the fundamental frequency?  Draw a diagram to illustrate your answer.

 

6. Interference

In the exam you are expected to know about:

  • The concepts of path difference and coherence

  • Requirements of two source and single source double-slit systems for the production of fringes

  • The appearance of the interference fringes produced by a double slit system.

  • Use of l = ws/D.

Review the Topic 6 Notes

Go to http://www.saburchill.com/physics/chapters2/0006.html

1. What is meant by constructive interference?  Draw a diagram to show two waves super-posing to interfere constructively.

2.  What phase relationship is needed for destructive interference to occur?

3. What path difference is needed for constructive interference?  What path difference is needed for destructive interference?

Look at http://www.saburchill.com/physics/chapters2/0007.html to observe interference patterns and http://www.saburchill.com/physics/chapters2/0015.html to show interference patterns with red and blue light.

4. What is the effect on the pattern of a shorter wavelength (i.e. blue light)?

Go to http://www.s-cool.co.uk/default.asp

Follow through to Physics, Oscillation and Waves, Progressive Waves and scroll down to Interference.

1. Draw a diagram to show a set-up for Young's Double Slit experiment.

2.  What is its associated formula?

3.  How are light and dark fringes formed?

4. Coherent Light is needed.  What is meant by this?

 

7. Diffraction

In the exam you are expected to know about:

  • Diffraction Appearance of the diffraction pattern from a single slit

  • The plane transmission diffraction grating at normal incidence

  • Optical details of the spectrometer will not be required

  • Derivation of  d sin θ= nλ

  • Applications, e.g. to spectral analysis of light from stars.

Review the Topic 6 Notes

Go to http://www.s-cool.co.uk/default.asp

Follow through to Physics, Oscillation and Waves, Polarisation and Diffraction.

1. What happens to a diffraction pattern if you make the gap smaller?

Go to http://www.saburchill.com/physics/chapters2/0014.html

1. What assumption is made?

2. Draw a diagram to show the path difference.

3. What is the equation?

4.  How is the equation changed if we state q in radians?

 

Theme 2 Capacitors

1. Capacitance

In the exam you are expected to:
  • Recall and use Q = CV.

Read the Topic 7 Notes. You may also find the notes in Electronics AS Topic 9 useful.

Go to http://www.saburchill.com/tech/electronics/elect006.html

1.  What is a capacitor?

2.  Draw the symbols for electrolytic and non-electrolytic types.

3.  What is the unit for capacitance?  What fraction are the most common units?

Go to http://www.s-cool.co.uk/default.asp

Follow through to Physics, Capacitors.

1.  How does a capacitor work.

2. Sketch a graph of charge against potential difference.

3. What feature of this graph is the capacitance?

4. What is the equation for the graph?

5. What is the definition of capacitance?

 

2. Energy Stored by a Capacitor

In the exam you are expected to know about:

  • Derivation and use of  E = 1/2 QV

  •  interpretation of area under a graph of charge against p.d.

Read the Topic 7 Notes. You may also find the notes in Electronics AS Topic 9 useful.

Go to http://www.s-cool.co.uk/default.asp

Follow through to Physics, Capacitors.

1. How is energy in a capacitor worked out?

2. Draw the graph.

3. What is the equation for the energy and how is it derived from the graph?

 

3. Graphical representation of charging and discharging of capacitors through resistors

In the exam you are expected to know about:

  • time constant = RC

  • Calculation of time constants including their determination from graphical data

Read the Topic 7 Notes. You may also find the notes in Electronics AS Topic 9 useful.

Go to http://www.s-cool.co.uk/default.asp

Follow through to Physics, Capacitors.

1. How is the time constant worked out?  What are the units (you may be surprised!)?

2. What proportion of the charge is left after the time RC?

3. What shape is the voltage discharge graph for a capacitor?

4. Is the shape different if charge or current are measured?

5.  How long does it take the current to reach zero?

 

4. Quantitative treatment of capacitor discharge

In the exam you are expected to know about:
  • Use of Q = Qo e-t/RC

Read the Topic 7 Notes. You may also find the notes in Electronics AS Topic 9 useful.

Go to http://www.s-cool.co.uk/default.asp

Follow through to Physics, Capacitors.

1.  What do the terms in the equation mean?

2.  Make sure that you know how to use natural logarithms.  ASK YOUR TEACHER if you are not sure.

3. What fraction of charge would be left after 4 RC seconds?

4. What would the equation be to describe the exponential decay in voltage?

5. Is the RC time constant (or the half-life) affected by the starting voltage?

 

 

Theme 3 - Gravitational and Electric Fields

1. Uniform motion in a circle

In the exam you are expected to know about:
  • w is angular speed
  • w = v/r
  • w = 2pf
  • a = v2/r = w2r

Review Topic 1 Notes

Go to http://www.physicsclassroom.com/Class/circles/U6L1a.html

1. How does the diagram of the bulbs mounted radially explain the concept of angular velocity?

2. What is the direction of the velocity vector at any point as it moves about a circular path?

3. What direction is the acceleration?  How can this be shown?

4.  What is the name give for this acceleration?

5.  What examples are given?

6.  Why is centrifugal force a dirty word?

Note that when they present the equation they use period T rather than frequency.

 

2. Centripetal force equation

In the exam you are expected to:
  • Recall and use the equation F = mv2/r

Review Topic 1 Notes

Go to http://www.physicsclassroom.com/Class/circles/u6l2a.html

1.  How is Newton II related to centripetal force?

Ignore the stuff about coefficient of friction.  Good physics but not on the syllabus.

 

3.  Gravity, Newton's Law, The Gravitational Constant, G

In the exam you are expected to:
  • Recall and use F = -GMm/r2

Review Topic 8 in the notes.

Go to http://www2.jpl.nasa.gov/basics/bsf3-2.html

1. How do satellites stay in orbit?

Go to http://www.physicsclassroom.com/Class/circles/circtoc.html.  Go to Lesson 3.

2.  Read how the equation for gravity is derived.

3.  What is the value for G? (DON'T try to learn it; it is on the data sheet!)  It was worked out by Henry Cavendish, whose family still own Chatsworth House in Derbyshire, and several tens of thousands of hectares throughout the country.  I have always liked the gardens.  The house is a bit overstated.

4.  Why is there a negative sign in the gravity equation?

5.  Have a go at the questions further down the page and use the pop-up answers to check that you have got them right.

 

4. Gravitational Field Strength g.

In the exam you are expected to:
  • Use g = F/m = -GM/r2 = -DV/Dr

If you can't remember the equation for force, look up the variants for g, and work back to it.  Personally I think it's daft having to remember formulae.  I think that students are better off spending time and energy in actually understanding the use of formulae rather than parrot learning.  There are many things that are daft in education, not least OFSTED, but that's a different story...

Review Topic 8 in the notes.

Carry on in Lesson 3 from http://www.physicsclassroom.com/Class/circles/U6L3e.html

1. What is the value of g?

2. Is it consistent to describe g as acceleration and force per unit mass?

3.  How does g change as we go from the Earth's Surface to a height of 1000 km?

4.  Where is g measured from?  Can you identify a bear trap?

5. Sketch a graph of g against distance.

6.  What is the value of g on Jupiter?  How does it compare with the Earth?

7.  Which other planets would you be able to walk comfortably on, i.e. not too light nor too heavy?

 

5.  Gravitational Potential V

n the exam you are expected to:
  • Use V = -GM/r
  • Understand graphical representations of V and  g against r.

Review Topic 8 in the notes

Go to http://users.hartwick.edu/hartleyc/oneOverR/oneOverR.html to see a 3-D representation of a gravity potential well.

Go to http://www.jcphysics.com/toolbox_indiv.php?sub_id=13

If you are a mathematician, you will understand the calculus derivation.  If not, ignore it.  Note that the author uses the code f for gravitational potential not V.

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=4&subject_id=2&ebt=181&ebn=&ebs=&ebl=&elc=13

Note that here they use F for gravitational potential, not V.

1.  What is meant by gravitational potential?

2.  What is the maximum possible value for V?

3.  Is V a vector or a scalar?

4.  What is meant by equipotential?

5.  What is the definition for V?

 

6. Motion of Masses in Gravitational Fields

In the exam you are expected to know about:
  • Motion of planets and satellites including geosynchronous orbits.

Review Topic 8 in the notes.

Go to http://www.physicsclassroom.com/Class/circles/U6L4b.html

1. What  is a satellite?

2. What are the principles used to explain how a satellite stays in orbit?

3. What is the direction of centripetal force?

4. For a satellite in orbit, what provides the centripetal force?

Bear trap:  Gravity is NOT balanced out by centrifugal force!

5.  What is meant by geostationary orbit?

 

7. Coulomb's Law.  Permittivity of Free Space, e0.

In the exam you are expected to recall and use:
  • F = [1/(4pe0 )] × Q1Q2/r2

Yes, you do have to learn this ghastly looking equation.  You know my thoughts about that.  The term e0 is called the permittivity of free space.  It has the value 8.99 × 109 Nm2 C-2 . It's in the datasheet so don't try to learn it.

Here's a little dodge:

1/(4pe0 ) = 9 × 109 C2 m-2 N-1 or m F-1

Don't bother with the units; I can't remember them either.  You will NOT lose marks for just writing 9 × 109.  However, if you try to quote the units, but do it wrong, an officious examiner may well dock you a mark for a contradiction.  Be warned!

So the relationship becomes:

F = 9 × 109  × Q1Q2/r2

Much easier!

Review Topic 9 in the notes.

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=1&subject_id=2&ebt=181&ebn=&ebs=&ebl=&elc=13

(If you can't follow this, simply go to www.s-cool.co.uk and follow the links.)

1.  What is meant by an electric field?

2.  Look at the worked examples on the equation F = [1/(4pe0 )] × Q1Q2/r2.  The examples are quite a long way down the page.

3. Why are the signs important?

 

8. Electric Field Strength, E

In the exam you are expected to know about:
  • Application, e.g. estimation of forces at closest approach in Rutherford alpha particle scattering.
  • E = F/Q = V/d (Uniform Field)
  • E = [1/(4pe0 )] × Q/r2 (radial field)

Review Topic 9 in the notes.

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=1&subject_id=2&ebt=181&ebn=&ebs=&ebl=&elc=13

1.  What is the definition of an electric field?  This applies to both radial and uniform fields.

2.  What are the units for E?  Both types of units are perfectly correct and consistent.

3. Draw a diagram to show the concept of a uniform field and (Harder, but not too hard) a radial field.

4. Have a look at the example.

5.  Why is E a vector?  What is the significance of the sign?

 

9. Electric Potential, V.

In the exam you are expected to know about:
  • V = [1/(4pe0 )] × Q/r

Review Topic 9 in the notes.

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=2&subject_id=2&ebt=181&ebn=&ebs=&ebl=&elc=13

1. What is the definition of potential V?  (A bit more than voltage, please!)

2.  What kind of unit is it?

3.  Work through the examples.

4.  What is meant by equipotentials?  Draw a diagram to illustrate your answer for both uniform and radial fields.

5.  (Harder) How could these be represented graphically?

 

10. Motion of charged particles in an electric field

In the exam you are expected to know about:
  • The trajectory of particle beams.

Review Topic 9 in the notes.

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=1&subject_id=2&ebt=181&ebn=&ebs=&ebl=&elc=13

1.  Look at the animated demonstration of the electron in a uniform field.

2. What shape is the path of the electron?  Why is it this shape?

3.  (Harder)  What would be the effect of inserting a proton into the field, travelling at the same speed as the electron from left to right?  Mass of a proton is about 1800 times that of an electron.

 

11. Similarities and differences between electric and gravitational fields

In the exam you are expected to know about:
  • How gravity and electric fields are alike, but no quantitative comparisons are required.

Review Topic 9 in the notes.

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=5&subject_id=2&ebt=181&ebn=&ebs=&ebl=&elc=13

1.  List the similarities you can think of in gravity and electric fields.  Then the differences.

2.  In the last section you looked at the trajectory of an electron in a uniform electric field.  What is the equivalent situation with a gravity field?

3.  Consider whether there is a gravitational analogy with the proton in the electric field.

 

 

Theme 4 - Magnetic Effect of  Electric Currents

1. Force on a current carrying wire in a magnetic field

In the exam you are expected to be able to use:
  • F = BIl

Review Topic 10 Notes

Go to http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=11&quicklearn_id=2&subject_id=2&ebt=177&ebn=&ebs=&ebl=&elc=13

1.  What is the magnetic field like between two opposite poles, N and S?

2. What is the magnetic field like around a current-carrying wire?

3. Look at the animated demonstration on the motor effect.

4. Draw a diagram to illustrate Fleming's Left Hand rule.

5.  What is the experiment to illustrate how force depends on current?

6.  How would you work out the magnetic field strength from that experiment?

 

2.  Motion of Charged Particles in a Magnetic Field

In the exam you are expected to know about and to use:
  • F = BQv
  • Circular path of charged particles
  • Applications, e.g. cyclotron.

Review Topic 10 Notes

Go to:

http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=11&quicklearn_id=4&subject_id=2&ebt=177&ebn=&ebs=&ebl=&elc=13

1. Do the electrons need to be in a wire?

2. What is the motion of the electrons?

3. What would be the difference if protons were used?

Ignore the Hall Effect;  excellent Physics but it's no longer on the syllabus!

An alternative site is:

http://www.saburchill.com/physics/chapters/0055.html

 

3  Magnetic flux density B, flux Φ, flux linkage N Φ

In the exam you are expected to know about:

  • Φ = BA , B normal to A

Review Topic 10 Notes.

Go to http://www.saburchill.com/physics/chapters/0056.html

1.  What is meant by flux density and flux?

2.  What are the units for Flux?

3.  What is flux linkage?

Note that in the syllabus you only have to know about flux when the magnetic field B is at 90 degrees to the area. 

 

4. Electromagnetic induction

In the exam you are expected to:

  • Describe simple experimental phenomena,

  • Know Faraday’s and Lenz’s laws

  • For a flux change at a uniform rate: magnitude of induced e.m.f. = NDF/Dt

  • Understand applications, e.g. p.d. between wing-tips of aircraft in flight.

Review Topic 10 Notes.

Go to http://www.saburchill.com/physics/chapters/0057.html

1. Which way must the wire be moved?

2. Note that for a single wire, e.m.f. = Blv.  This is quite useful for the aircraft in a magnetic field.

Go to http://www.saburchill.com/physics/chapters/0059.html

3. What is Faraday's Law?

Go to http://www.saburchill.com/physics/chapters/0058.html

4. What is Lenz's Law?

Note that the correct formula is E= -NDF/Dt.  The minus sign tells us that the induced emf opposes the change.  If the minus sign wasn't there, the emf would help the change.  Therefore if you put a load on a generator, it act as a motor in the same way as the driving engine; it would run faster.  Instead, a load on a generator acts as a motor in the opposite direction, so the engine has to work harder.

 

 

Theme 5. Nuclear applications

1. Mass and energy

In the exam you are expected to know about:

  • Simple calculations on nuclear transformations; mass difference;

  • binding energy

  • Atomic mass unit, u

  • Conversion of units; 1u = 931.1 MeV

    •

  • E = mc²

  • Appreciation that E = mc² applies to all energy changes

  • Graph of average binding energy per nucleon against nucleon number, A

  • Fission and fusion processes.

Review the Topic 11 notes.

Surprisingly there isn't much else about this on the Web that is suitable at this level, so you will have to stick with me, I'm afraid!  If you do find something, please tell me.

1.  What is the atomic mass unit?

2. What is meant by mass defect?

3. How is mass defect related to the energy?  What is this energy used for?

4. Sketch a graph pf binding energy per nucleon against the nucleon number.

5. What are the key features of the graph?

6. What is meant by fission?

7.  What is fusion?

 

2. Induced Fission

In the exam you are expected to know about:

  • Induced fission by thermal neutrons

  • Possibility of a chain reaction

  • Critical mass

  • Need for a moderator in thermal reactors

  • Control of the reaction rate

  • Factors influencing choice of material for moderator, control rods

  • and coolant

  • Examples of materials

Review the Topic 12 Notes

Go to http://www.bnfl.com/index.aspx?page=150 to read about this in more depth.

1.  What are thermal neutrons?

2. What happens in fission?  Why is a critical mass needed?

3. Describe the key features of a nuclear power stations.  What are the similarities between a nuclear power station and a coal-fired power station?

 

3. Safety aspects

In the exam you are expected to know about:

  • Fuel used, shielding, emergency shut-down

  • Production, handling and disposal of active wastes.

Review the Topic 12 Notes

Go to http://www.bnfl.com/index.aspx?page=2 to read about this in more depth.

1.  What are the advantages of nuclear power?

2.  What are the disadvantages?

3. How would an emergency shut down be done?

4. What are the different kinds of waste materials? How are they stored?

Go to http://www.ida.liu.se/~her/npp/demo.html which is a good applet that allows you to control a nuclear power station when there are failures.  It's harder than you think.

 

4. Artificial transmutation

In the exam you are expected to know about:

  • Production of man-made nuclides and examples of their practical applications, e.g. in medical diagnosis

Review the Topic 12 Notes.

1. Write down two ways in which elements can be transmutated.

2. What happens to the mass defect?  Where does the energy come from?

3. State a use for radionuclides produced by artificial transmutation.

Amersham Laboratories produce radionuclides for medical and biological research purposes.  Visit their website at http://www.amersham.com/businesses/index.html.