Capacitance

Look at the website linked below and try the exam style questions
http://www.s-cool.co.uk/a-level/physics/capacitors/revise-it/time-constant-and-energy-stored-in-capacitors

Return of A-level club Tuesdays in W8

Physics drop-in
At least one Physics teacher will be available every Tuesday after school from 3.00- 4.00pm to help with your Physics needs.  Bring some work to do, e.g. questions, homework you are stuck with, or come with things to ask about.
We will be operating a loyalty card system with an end of year reward for the person with the most points!
Thanks and hope to see you there
Ms H

The Magnetism of Magnetism (Talk)

The Magnetism of Magnetism (Talk) at Oxford Physics Dept

Wednesday 13^th November 2013, 6pm-7pm

In this talk we explore the ways in which our desire to unpick the tantalizing mysteriousness of magnetism has shaped—and continues to shape—science and technology as we know it. Further information and booking: http://www2.physics.ox.ac.uk/events/2013/11/13/the-magnetism-of-magnetism

Turning points significance questions

Questions
1.Give one reason why Huygens’ wave theory of light did not replace Newton’s theory of light when the fringe pattern due to double slits was first observed. (1)

2.The interference fringe pattern observed by M’n’M on their interferometer did not shift when the apparatus was rotated by 90°. Explain the significance of this null observation. (1)

3.   Discuss the significance of Einstein’s explanation of the photoelectric effect. (2)

4.   Millikan found that the charge on an oil droplet was always in multiples of e. Explain the significance of this result. (1)

5.   What was the significance of Thompson’s calculations of the specific charge of an electron? (2)

Answers

1.Newton’s scientific pre-eminence/ reputation
No evidence that light travelled slower in water or glass
(as predicted by Huygens’ theory)
Huygens’ theory considered light waves as longitudinal
and therefore could not explain polarisation(1)

2.The speed of light does not depend on the motion of the light source  or of the observer(1)

3.the photon is the quantum of em radiation/light (1)
classical wave theory could not explain threshold frequency (1)
classical wave theory was replaced by the photon theory (1)
[or photons can behave as waves or particles]

4.Shows that charge is quantised – comes in “packets” of 1.6 x 10-19C

5.Bigger than any specific charge measured before; 1840 x bigger than that of H nucleus; therefore electron is very small (or has huge charge)

Turning points summary

Name	Nationality	Dates	Interesting fact	What did he do?	Significance
Albert Einstein	Austrian	1905	Published over 450 papers, 150 of them non-scientific	Published photon theory of light and used it to explain the photoelectric effect; published theory of special relativity	First to say that light consisted of packets of energy called photons, beginnings of quantum theory
Isaac Newton	British	1704 ish	Built the first telescope	Put forward theory that light was made of particles called corpuscles	Not a lot; he was basically wrong, for once.  Reputation is sometimes more important than facts
Robert A Millikan	American	1915	May have fudged some of his results to make them more convincing	First accurate measurement of the charge on an electron	Found that charge was quantised into multiples of e, 1/6 x 10-19C
Heinrich Hertz	German	1885	Discovered photoelectric emission	Discovered how to produce and detect radio waves	Showed that Maxwell was right – energy as waves can travel from source to detector
James Clark Maxwell	Scottish	1865	Died age 36	Gave mathematical proof that light consists of electromagnetic waves	Showed that light was a wave with a constant speed, also predicted existence of other EM waves outside the visible spectrum
Max Planck	German	1900	His son was executed for his part in the failed assassination attempt on Hitler	Energy of a photon is proportional to its frequency related by h, Planck’s constant	Founder of quantum theory
JJ Thompson	British	1897	Seven of his research assistants and his son won Nobel prizes	Discovered Cathode rays, measured the specific charge of an electron	Showed that e/m for an electron was 1860 times bigger than anything ever measured before
Thomas Young	British	1804	Deciphered the Rosetta Stone	Showed that light behaved as a wave with his double slit experiment	Refuted Isaac Newton’s corpuscular theory once and for all
Christiaan Huygens	Dutch	1678	Invented the pendulum clock	Put forward theory that light is a wave not a particle	He was right but didn’t have a lot of evidence
Louis de Broglie	French	1924	Got his first degree in humanities before turning to Physics	Put forward the idea of electron waves	He proposed the wave particle duality theory of matter, creating a new field in Physics
Albert Michelson and Edward Morley	American	1887	Worked on the atomic weight of oxygen for 11 years	Tried to detect the ether with an interferometer	Showed that there was no ether and also that the speed of light is constant.  Most important failed experiment in this unit

Past papers

Papers, markschemes and examiners reports can be found at the link below

http://www.aqa.org.uk/subjects/science/a-level/physics-a-2450/spec-at-a-glance

ISA preparation - DO IT NOW!

Remember the ISA is on Tuesday 19th Feb
Homework - finish the test paper and mark it - links below
Do the other past papers and use the guide, all on this blog under February /March 2012 - there are four papers to do, do them all and come to Monday's lesson with any queries you have.

Click on the links below to access the markscheme and paper for the practice ISA we did in class
Oscillation markscheme
http://www.scribd.com/doc/124773091/PHY6T-Q12-Final-Mark-Guide?secret_password=1rtfy7n7b32wpfnlker7
Oscillation test paper
http://www.scribd.com/doc/124773547/Phy6t-q12-Test?secret_password=wftl4gpid8u4mwrjltq

Good luck and happy half term!
Ms H

Physics events; Discovering planets from your sofa, stargazing and neutrinos

The next three Physics events at the Physics department are detailed below, booking is now open, hope to see you there!

http://www2.physics.ox.ac.uk/events

How to discover a planet from your sofa, and other adventures.

Date: 11 Mar 2013 - 6:00pm - 7:00pm

Venue: Martin Wood Complex, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU

Audience: General public (Age 12+)

Oxford astronomer and BBC Sky at Night co-presenter Chris Lintott invites you to the magical world of the Zooniverse, where you can discover planets, explore distant galaxies and even travel on World War 1 ships without leaving your browser. The Zooniverse is the world's most popular collection of citizen science projects, which use the power of human pattern recognition to help scientists deal with millions of images and gigabytes of data.

Neutrino - the invisible messenger

Date: 18 Mar 2013 - 6:00pm - 7:00pm

Venue: Martin Wood Complex, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU

Audience: General public (Age 14+)

Neutrinos are the most abundant particle in the universe and yet very little is known about them. They have no charge and are at least ten millions time lighter than the electron. They see almost all matter as transparent as vacuum which makes them very difficult to study. Without the existence of large source of neutrinos like the sun, cosmic rays or man-made nuclear reactors we may have never known about them.

Date: 19 Mar 2013 - 6:00pm - 9:00pm

Venue: Denys Wilkinson Building, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH

Audience: General public (Age 8+)

Stargazing Oxfordshire - Astronomy Evening

Find out more about research in astrophysics from professional scientists, and observe the night sky with your local community astronomers.

Simple harmonic motion ISA practice - HW

Simple harmonic motion ISA practice

1.       How did you ensure that the ruler was horizontal and the spring was vertical? (lie if necessary)(1)

2.       Describe and explain two techniques you used to ensure accurate timing (4)

3.       Describe what your graph suggests about the relationship between T² and m (2)

4.       Evaluate the reliability of your results(1)

5.       Describe the effect on your graph of using a ruler with a greater mass(2)

6.       What is the uncertainty in your smallest measurement of T?(1)

7.       What is the percentage uncertainty in your smallest measurement of T?(1)

8.       What is the percentage uncertainty in your smallest measurement of T²?(2)

Mars Lecture - Monday 4th Feb 6pm, free

Milankovic on Mars

Date: 4 Feb 2013 - 6:00pm - 7:00pm

Venue: Martin Wood Complex, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU

Room: Martin Wood Lecture Theatre

Audience: General public (Age 14+)

The surface and atmosphere of Mars continue to be the target for intensive exploration by robotic spacecraft such as NASA's Curiosity Rover and Mars Reconnaissance Orbiter, and the results are being modeled in increasing detail using sophisticated numerical models, much like the ones used to predict climate variability on Earth - with Oxford playing an important role in both kinds of activity. It now seems clear that, as on Earth, the Martian climate is very dynamic and continually changing and evolving, at least partly in response to cyclic changes in the planet's orbit and rotation on millennial to million year timescales. This is much like the orbital cycles on Earth that control the onset of ice ages, discovered by Milutin Milankovic in the early 20th century. In this talk we will explore the evidence for geologically recent and fairly extreme climate changes on Mars, examining the implications for where water (thought to be essential for any prospect of life) resides in the Martian environment, both now and in Mars' past and future.

Mini bio

Peter Read is a Professor in the Department of Physics, and Fellow and Tutor in Physics at Trinity College, University of Oxford, UK. In the Department he is currently Head of Atmospheric, Oceanic & Planetary Physics, which is one of the six sub-Departments within Oxford Physics.