Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Jack Sarfatti wikipedia , lookup
Aristotelian physics wikipedia , lookup
Renormalization wikipedia , lookup
Nuclear physics wikipedia , lookup
List of unusual units of measurement wikipedia , lookup
History of subatomic physics wikipedia , lookup
History of physics wikipedia , lookup
Max Planck Institute for Extraterrestrial Physics wikipedia , lookup
Condensed matter physics wikipedia , lookup
A-Level Course Notes: PHYSICS SECTION I: General Physics SECTION I General Physics CIE A-Level [AS and A2] ________________________ Course Notes DIPONT Educational Resource - Science 1 A-Level Course Notes: PHYSICS SECTION I: General Physics Syllabus Details______________________ DIPONT Educational Resource - Science 2 A-Level Course Notes: PHYSICS SECTION I: General Physics 1. Physical Quantities and Units_______________ Content 1.1 Physical quantities [AS] 1.2 SI Units [AS] 1.3 The Avogadro constant [A2] 1.4 Scalars and vectors [AS] Learning outcomes_____________________________________ Candidates should be able to: (a) show an understanding that all physical quantities consist of a numerical magnitude and a unit Physical Quantity 25 ms-2 Unit Numerical magnitude From the syllabus... DIPONT Educational Resource - Science 3 A-Level Course Notes: PHYSICS SECTION I: General Physics DIPONT Educational Resource - Science 4 A-Level Course Notes: PHYSICS SECTION I: General Physics DIPONT Educational Resource - Science 5 A-Level Course Notes: PHYSICS SECTION I: General Physics (b) recall the following SI base quantities and their units: mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol) Base Quantity length mass time electric current temperature amount of substance Unit meter kilogram second ampere kelvin mole Symbol m kg s A K mol (c) express derived units as products or quotients of the SI base units and use the named units listed in this syllabus as appropriate Example of derived units Quantity SI Derived Unit Symbol Unit SI Base Unit frequency hertz Hz - s-1 force newton N - m·kg·s-2 pressure, stress pascal Pa N/m2 m-1·kg·s-2 energy, work, quantity of heat joule J N·m m2·kg·s-2 power, radiant flux watt W J/s m2·kg·s-3 electric charge, quantity of electricity coulomb C - electric potential difference, electromotive force volt V W/A m2·kg·s-3·A-1 capacitance farad F C/V m-2·kg-1·s4·A2 electric resistance ohm V/A m2·kg·s-3·A-2 electric conductance siemens S A/V m-2·kg-1·s3·A2 magnetic flux weber Wb V·s m2·kg·s-2·A-1 kg·s-2·A-1 m2·kg·s-2·A-2 s·A magnetic flux density tesla T Wb/m2 inductance henry H Wb/A Celsius temperature degree Celsius °C - K (c) luminous flux lumen lm cd·sr illuminance lux lx lm/m2 activity (of a radionuclide) becquerel Bq - m2·m-2·cd = cd m2·m-4·cd = m-2·cd s-1 (d) use SI base units to check the homogeneity of physical equations Each side of an equation must have the same base units F = [N] = -2 [mkgs ] = DIPONT Educational Resource - Science m [kg] [kg] x a [ms-2] [ms-2] 6 A-Level Course Notes: PHYSICS SECTION I: General Physics (e) show an understanding of and use the conventions for labelling graph axes and table columns as set out in the ASE publication Signs, Symbols and Systematics (The ASE Companion to 16–19 Science, 2000) CONVENTIONS FOR TABLES (From the syllabus) DIPONT Educational Resource - Science 7 A-Level Course Notes: PHYSICS SECTION I: General Physics CONVENTIONS FOR GRAPHS (From the syllabus) Dependent variable / units Plotting graphs Best fit line Steepest Gradient Maximum intercept Shallowest Gradient Error Bars Minimum intercept DIPONT Educational Resource - Science Independent variable / units 8 A-Level Course Notes: PHYSICS SECTION I: General Physics (f) use the following prefixes and their symbols to indicate decimal submultiples or multiples of both base and derived units: pico (p), nano (n), micro (μ), milli (m), centi (c), deci (d), kilo (k), mega (M), giga (G), tera (T) (g) make reasonable estimates of physical quantities included within the syllabus Remember: an estimate does not have to be exactly correct and often just expresses an order of magnitude. e.g. The mass of universe is ~1050 kilograms (h) show an understanding that the Avogadro constant is the number of atoms in 0.012 kg of carbon-12 The Avogadro number: The number of atoms in 0.012kg of carbon-12. It is 6.02x1023 (i) use molar quantities where one mole of any substance is the amount containing a number of particles equal to the Avogadro constant Mole: One mole of a substance is the amount of that substance that contains the same number of atoms as 0.012kg of carbon-12. Molar Mass: The mass of one mole of a substance is called the molar mass. DIPONT Educational Resource - Science 9 A-Level Course Notes: PHYSICS SECTION I: General Physics (j) distinguish between scalar and vector quantities and give examples of each Vector: Scalar: Quantity with both magnitude and direction Quantity with only magnitude Vectors Scalars Displacement Distance Velocity Speed Acceleration Mass Force Energy Momentum Temperature Electric Field Strength Potential Difference Magnetic Field Strength Density Gravitational Field Strength Area (k) add and subtract coplanar vectors Vector addition and subtraction 4N 7N = 3N 4N = 5N 3N 4N = 1N 3N DIPONT Educational Resource - Science 10 A-Level Course Notes: PHYSICS SECTION I: General Physics (l) represent a vector as two perpendicular components. x sin Vector components x x cos SEE PHET SIM DIPONT Educational Resource - Science 11 A-Level Course Notes: PHYSICS SECTION I: General Physics 2. Measurement Techniques___________________ Content 2.1 Measurements 2.2 Errors and uncertainties Learning outcomes_____________________________________ Candidates should be able to: (a) use techniques for the measurement of length, volume, angle, mass, time, temperature and electrical quantities appropriate to the ranges of magnitude implied by the relevant parts of the syllabus. In particular, candidates should be able to: • measure lengths using a ruler, vernier scale and micrometer Micrometer Vernier DIPONT Educational Resource - Science 12 A-Level Course Notes: PHYSICS SECTION I: General Physics When using a ruler, be careful of parallax errors • measure weight and hence mass using spring and lever balances • measure an angle using a protractor • measure time intervals using clocks, stopwatches and the calibrated timebase of a cathode-ray oscilloscope (c.r.o.) • measure temperature using a thermometer as a sensor • use ammeters and voltmeters with appropriate scales • use a galvanometer in null methods Voltage measurements Galvanometer multiplier Galvanometer Current measurements Shunt A Galvanometer is a current measuring meter that can be used in two ways… With a resistor in series to measure voltage With a resistor in parallel to measure current DIPONT Educational Resource - Science 13 A-Level Course Notes: PHYSICS SECTION I: General Physics • use a cathode-ray oscilloscope (c.r.o.) KEY CONTROLS…. Time base: Time taken for beam to pass through one horizontal division [Sec/div] Vertical amplifier gain: The vertical scale control [Volts/div] • use a calibrated Hall probe Basic Structure of a Hall probe… A small piece of semi-conductor material placed perpendicular to the magnetic field A current is paced through the semi-conductor A voltage (Hall voltage) is measured which is proportional to the magnetic flux density DIPONT Educational Resource - Science 14 A-Level Course Notes: PHYSICS SECTION I: General Physics (b) use both analogue scales and digital displays Analogue and Digital Displays Digital Scale Analogue Scale Error is half the smallest division +/- 2.5 Error is the last decimal place +/- 0.01 (c) use calibration curves Real value Calibration curve Measured value Record value from instrument Use calibration curve to read off the corrected “real” value DIPONT Educational Resource - Science 15 A-Level Course Notes: PHYSICS SECTION I: General Physics (d) show an understanding of the distinction between systematic errors (including zero errors) and random errors Random Errors Systematic Errors Changes conditions or surroundings of equipment Zero error on instrumentation Non-perfect observations by experimentalist Wrong calibration of instrumentation Readability of equipment Incorrect measurement method for every measurement Random Errors: Errors that can not be predicted. Systematic Errors: Errors which are the same for each measurement (e) show an understanding of the distinction between precision and accuracy Small random error Small systematic error # of measurements Imprecise and accurate Precise and accurate # of measurements Precision: Accurate: reading reading value Imprecise and inaccurate # of measurements # of measurements value Precise and inaccurate reading reading value DIPONT Educational Resource - Science value 16 A-Level Course Notes: PHYSICS SECTION I: General Physics (f) assess the uncertainty in a derived quantity by simple addition of actual, fractional or percentage uncertainties (a rigorous statistical treatment is not required). Absolute uncertainty: Fractional uncertainty: Percentage uncertainty: Size of an error and its units Absolute uncertainty / measurement Fractional uncertainty x 100% Addition and Subtraction 5.9 ±0.6m + 3.9 ±0.8m = 9.8 ±1.4m (add absolute errors) 6.9 ±0.6m - 3.9 ±0.8m = 3.0 ±1.4m (add absolute errors) Multiplication and Division 5.6 ±0.5m x 2.6 ±0.5m = 15 ±??m 0.5 / 5.6 = 0.089 0.5 / 2.6 = 0.19 Sum of relative errors = 0.28 Absolute error = 0.28 x 15 = 4.2m FINAL ANSWER = 15 ±4 m DIPONT Educational Resource - Science 17 A-Level Course Notes: PHYSICS SECTION I: General Physics Background Reading_________________ PHYSICS, Giancoli 6th edition, Chapter 1 Useful Websites______________________ http://phet.colorado.edu/en/simulations/category/new http://www.s-cool.co.uk/alevel/physics.html http://www.physicsclassroom.com/mmedia/index.cfm http://www.phys.hawaii.edu/~teb/java/ntnujava/index.html http://www.colorado.edu/physics/2000/index.pl Constants___________________________ [These are given on each test paper] DIPONT Educational Resource - Science 18