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Author Archives: KEV KNOWLES

Capacitor Charging-Discharging

Friday, July 1st, 2011 | KEV KNOWLES | No Comments

I’ve set up a virtual lab for you to investigate how a capacitor charges and discharges.

  1. Download this file : Capacitor
  2. Open the AC&DC circuit construction kit here
  3. Load the capacitor file. It will display a capacitor circuit.
  4. Add the voltage chart with the connections across the capacitor [red to the left, black to the right]
  5. Add the current chart with the connection beside the red V connector.
  6. The capacitor charges through the top loop [and switch]
  7. It discharges through the bottom loop.
  8. You can investigate the following
    1. Change the supply voltage Vs [initial 10V]
    2. Change the capacitance [initial 0.1F]
    3. Change the charge resistance [initial 10 ohm]
    4. Change the discharge resistance [initial 5 ohm]
  9. You could also use the built in stopwatch to investigate the time constant

Teacher Guides from Howard Hughes Medical Institute

Monday, June 13th, 2011 | KEV KNOWLES | No Comments

These teacher guides were developed to provide topic-specific organization of BioInteractive resources optimized for classroom use. The guides offer detailed instructions for both online and DVD access, time lengths, and summaries of each resource. The resources include animations, video clips, virtual labs, lecture chapters, and interactive Click and Learns specific to each topic – Biotechnology, DNA, gene expression, gene regulation etc


Brilliant resources appropriate for classroom teaching here.
http://www.hhmi.org/biointeractive/guides/

The Biology Corner

Monday, June 13th, 2011 | KEV KNOWLES | No Comments

The Biology Corner is a resource site for biology and science teachers.  It contains a variety of lessons, quizzes, labs, web quests, and information on science topics.   You can find lessons related to biology topics in the links  listed under “topics” on the sidebar.  Topics include:  Ecology, Genetics, Anatomy, Cells, Scientific Method, and Evolution.
Great resources here for student revision also!   Really useful revision tools, plus even has a virtual dissection or two!
http://www.biologycorner.com/

LRC Circuit Simulator

Monday, May 30th, 2011 | KEV KNOWLES | No Comments

All singing and dancing LRC applet.

You can control all basic values L, R, C , V0 [peak V] &  f [omega].

The applet will display the voltage traces for resistor, inductor and capacitor, plus the current in the circuit. It also calculates the reactances and impedance [showing the vector sum as well] showing them as phasors for good measure.

All you need to know.

http://www.ngsir.netfirms.com/englishhtm/RLC.htm

Mechanics

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves knowledge and understanding of phenomena, concepts, principles and/or relationships related to translational; circular and rotational; and simple harmonic motion; and the use of appropriate methods to solve related problems.

Translational Motion

  • Centre of mass (1 and 2 dimensions)
  • conservation of momentum and impulse (2 dimensions only)

Circular and Rotational Motion

  • Velocity and acceleration of, and resultant force on, objects moving in a circle under the influence of 2 or more forces, eg banked corners, vertical circles
  • Newton’s Law of gravitation
  • satellite motion
  • Rotational motion with constant angular speed and with constant angular acceleration
  • torque
  • rotational inertia
  • angular momentum
  • rotational kinetic energy
  • conservation of angular momentum
  • conservation of energy

Simple Harmonic Motion (SHM)

  • Displacement; velocity; acceleration
  • time and frequency of a particle undergoing SHM
  • forced SHM
  • resonance
  • the reference circle
  • phasors
  • conservation of energy.

Atomic Physics

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves knowledge and understanding of phenomena, concepts, principles and/or relationships related to atoms, photons and nuclei, and the use of appropriate methods to solve related problems.

  • The Bohr model of the hydrogen atom
  • the photon; the quantisation of energy
  • discrete atomic energy levels; electron transition between energy levels; ionisation; atomic line spectra (infrared, visible and ultraviolet)
  • the photoelectric effect; the electron volt
  • description of the particle/wave duality of light
  • nuclear binding energy and mass deficit; conservation of mass-energy for nuclear reactions.

Waves

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves knowledge and understanding of phenomena, concepts, principles and/or relationships related to wave systems, and the use of appropriate methods to solve related problems.

  • Interference (quantitative) of electromagnetic and sound waves
  • multi-slit interference and diffraction gratings
  • standing waves in strings and pipes
  • harmonics and overtones
  • resonance
  • beats
  • Doppler Effect (stationary observer).

Electro-Magnetism

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves knowledge and understanding of phenomena, concepts, principles and/or relationships related to direct current (DC) circuits, capacitance, electromagnetic induction, alternating current (AC) circuits, and the use of appropriate methods to solve related problems.

DC Circuits and Capacitance

  • Internal resistance; simple application of Kirchhoff’s Laws
  • parallel plate capacitor; capacitance; dielectrics; series and parallel capacitors; charge/discharge characteristics of capacitors in DC RC circuits; voltage/time and current/time graphs for a capacitor; time constant; energy stored in a capacitor.

Electromagnetic Induction and AC Circuits

  • Magnetic flux; magnetic flux density; Faraday’s Law; Lenz’s Law; voltage/time and current/time graphs for an inductor; time constant; self inductance; the inductor; energy stored in an inductor
  • mutual inductance; the transformer
  • the comparison of the energy dissipation in a resistor carrying direct current and alternating current; peak and rms voltage and current; phase
  • phasors in AC; reactance and impedance and their frequency dependence in a series circuit; voltage and current and their phase relationship in LR and CR series circuits; resonance in LCR circuits.

Particles

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves describing properties of atoms, molecules, and ions, and thermochemical principles.

Properties of particles include:

  • electron configuration of atoms and ions of the first 36 elements (using s,p,d notation)
  • special characteristics of transition metals (variable oxidation state, colour) related to electron configuration. Transition metals will be limited to iron, vanadium, chromium, manganese, copper and zinc
  • periodic trends in atomic radius, ionisation energy, and electronegativity, and comparison of atomic and ionic radii
  • Lewis structures and shapes (up to six electron pairs about the central atom for molecules and polyatomic ions, including those with multiple bonds)
  • polarity of molecules
  • attractive forces between atoms, ions, and molecules. These will include ionic bonds, covalent bonds, and intermolecular attractions due to temporary dipoles and permanent dipoles (including hydrogen bonding).

Thermochemical principles include:

  • transfer of heat between the system and the surroundings
  • calculations involving the use of specific heat capacity
  • ΔcH°, ΔfH°, ΔrH°, ΔvapH°, ΔsubH°, and ΔfusH°
  • Hess’s Law including application of ΔrH(= ΣΔfH((products) – ΣΔfH((reactants)
  • bond enthalpies.

Equilibrium

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves describing properties of aqueous systems using equilibrium principles.

Aqueous systems are limited to those in which proton transfer occurs and those involving a sparingly soluble ionic solid.

Properties of aqueous systems are related to the nature and the concentration of the species present in the solution. Description, explanation and application, or discussion of these properties may be qualitative and/or quantitative.

Qualitative evidence may include

  • correlation between acid or base strength, Ka and pH
  • relative equilibrium concentrations of dissolved species
  • variability in solubility of a sparingly soluble salt due to the formation of a complex ion, the addition of a common ion, or the reaction of a basic anion with added acid
  • features of titration curves including buffer region, equivalence point and selection of indicator (titrations of weak acids with weak bases are excluded)
  • the nature of buffer solutions.

Quantitative evidence includes calculations involving

  • Ka, Kw and pH limited to
    • solutions of bases, monoprotic acids and buffers
    • those in which the extent of reaction is small so that the equilibrium concentration of a dissolved weak acid can be approximated by the initial concentration, ie [HA] = c(HA)
    • pH at a particular point in a titration;
  • Ks and solubility limited to
    • AB, A2B and AB2 type solids where neither of the ions A or B react further with water
    • calculating the concentration of one ion given the other
    • calculating the solubility in water and in solutions already containing one of the ions A or B (a common ion)
    • predicting precipitation or dissolution.

Organic

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves describing the structure, physical properties, and reactions of organic compounds.

Aspects of organic chemistry includes:

  • structures of organic compounds including constitutional isomers and enantiomers
  • naming of organic compounds using IUPAC conventions
  • physical properties of organic compounds
  • reactions of organic compounds.

Organic compounds are limited to those containing one or more of the following functional groups: alkene, haloalkane, amine, alcohol, aldehyde, ketone, ester, carboxylic acid, acyl chloride, amide.

Structures and names of organic compounds are limited to those compounds containing no more than eight carbons.

Physical properties of organic compounds are limited to solubility, melting point, boiling point, rotation of plane-polarised light.

Reactions of organic compounds include acid-base, oxidation, elimination and substitution reactions. Substitution reactions include esterification, hydrolysis, and polymerisation.

  • acid-base is limited to reactions of carboxylic acids, amines, and carboxylate and alkylammonium salts
  • oxidation is limited to reactions using the following reagents: MnO4–/H+, Cr2O72–/H+, Tollens’, Fehling’s and Benedict’s
  • elimination is limited to reactions using the following reagents: KOH in alcohol and concentrated H2SO4
  • substitution is limited to reactions using the following reagents: concentrated HCl, HBr, SOCl2, PCl3, PCl5, NaOH, KOH (in alcohol or aqueous solution), NH3, primary amines, primary alcohols/H+, primary alcohols, H2O/H+, H2O/OH–
  • polymerisation is limited to formation of polyesters and polyamides including proteins.

Redox

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves describing oxidation-reduction processes.

Processes involve reactions and calculations, which may include electrochemical cells and their properties, the use of reduction potentials, and spontaneity of oxidation-reduction reactions.

Calculations may include determination of oxidation numbers, mole ratios and those related to electrochemical cells.

  • Knowledge of appearance and state of the following reactants and the product to which they are converted in an oxidation-reduction reaction is required.
  • Oxidants will be limited to: O2, Cl2, I2, Fe3+, dilute acid (with metals), H2O2, MnO4– (reacting in acidic, basic or neutral conditions), Cu2+, Cr2O72–/H+, OCl–, concentrated HNO3, IO3–, MnO2.
  • Reductants will be limited to: metals, C, CO, H2, Fe2+, Br–, I–, H2S, SO2, SO32–, S2O32–, H2O2, H2C2O4.
  • Appropriate information relating to other oxidants or reductants will be provided.

Human Evolution

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves the description of trends in human biological evolution, cultural evolution, and patterns of dispersal.

Trends refers to progressive change over a period of time in relation to:

  • human biological evolution
  • human cultural evolution
  • patterns of dispersal of hominins. The term hominins refers to living and fossil species belonging to the human lineage. This is a subgroup of hominids which includes both humans and the great apes.

Trends in human biological evolution begin with early bipedal hominins and may require comparison with living hominids (apes). Trends are limited to:

  • skeletal changes linked to bipedalism
  • changes in skull and endocranial features
  • changes in the manipulative ability of the hand.

Trends in human cultural evolution will be limited to evidence relating to: use of tools (stone, wood, bone), fire, shelter, clothing, abstract thought (communication, language, art), food-gathering, and domestication of plants and animals.

  • Interpretations on the origins and trends of human evolution will be based on current evidence and may change as a result of recent developments.
  • Evidence relating to human evolution must be scientific evidence which is widely accepted and presented in peer-reviewed scientific journals.

Speciation

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves the description of processes and patterns of evolution.

Processes of evolution are limited to

  • ways in which speciation occurs (sympatric, allopatric)
  • reproductive isolating mechanisms that contribute to speciation (geographical, temporal, ecological, behavioural, structural barriers, polyploidy)
  • the role of natural selection.

Patterns of evolution will be selected from: convergent evolution, divergent evolution (including adaptive radiation), co-evolution, punctuated equilibrium, gradualism.

Plants & Animals

Monday, May 23rd, 2011 | KEV KNOWLES | No Comments

This achievement standard involves the description of animal behaviour and plant responses in relation to environmental factors.

Animal behaviour and plant responses will be selected from those relating to:

  • orientation (tropisms, nastic responses, taxes, kineses, homing, migration)
  • timing (annual, daily, lunar, tidal)
  • interspecific relationships (predation, parasitism, mutualism, commensalism, competition for resources)
  • intraspecific relationships (territoriality, cooperative interactions, reproductive behaviours, hierarchical behaviour, competition for resources).

The relationship of environmental factors to behaviour/response may be in terms of the process involved or the adaptive significance.