State four methods used to increase the accuracy of measurements in experiments.

Timing over multiple oscillations, using a fiducial marker, using a set square, or using a plumb line.

What instruments are used to measure small distances, and what types of scales might they have?

Callipers and micrometers, which may have digital or vernier scales.

When constructing circuits from circuit diagrams, what must be considered for certain components?

Polarity must be considered for components where it is important (such as diodes, LEDs, and electrolytic capacitors).

WJEC AS-Level Physics 1420QS

Basic Physics

Topic overview Units and quantities Scalars, vectors and density Moments, centre of gravity and equilibrium Prefixes, derived units and unit conversion Adding coplanar vectors and the triangle of forces Resolving forces on an inclined plane Taking moments: beams, ladders and stability

Kinematics

Topic overview Describing motion Equations of motion and free fall Projectile motion Non-uniform acceleration and curved motion graphs Projectiles launched at an angle Measuring speed, acceleration and g in the laboratory

Dynamics

Topic overview Newton's second law and momentum Force and Newton's laws Impulse and the force–time graph Collisions and explosions in one dimension Free body diagrams and connected bodies Newton's third law pairs and everyday forces

Energy Concepts

Topic overview Work and power Conservation of energy and efficiency The work–energy relationship Gravitational potential energy and energy interchange Elastic potential energy and the force–extension graph Power, velocity and the efficiency of machines

Solids Under Stress

Topic overview Stress, strain and the Young modulus Stress–strain graphs and the behaviour of materials Measuring the Young modulus, and material properties Hooke's law and elastic strain energy Crystalline, amorphous and polymeric solids Dislocations, ductile and brittle fracture

Using Radiation to Investigate Stars

Topic overview Stellar spectra and black bodies Wien's law, Stefan's law and stellar properties The inverse square law and stellar distance Finding the radius and temperature of a star Multiwavelength astronomy

Particles and Nuclear Structure

Topic overview Quarks, leptons and hadrons The four interactions and conservation laws The first generation of quarks and leptons Antiparticles and annihilation Baryons, antibaryons and mesons Deducing quark compositions from charge Beta decay and quark flavour change Testing a reaction against the conservation rules

Conduction of Electricity

Topic overview Current, charge and the ampere Drift velocity and the equation I = nAvq The coulomb and the charge on an electron Conductors, insulators and other charge carriers The free-electron model and the speed of conduction

Resistance

Topic overview Calculating resistance from resistivity Potential difference, Ohm's law and power Resistivity, temperature and superconductivity The volt: energy transferred per unit charge Current–voltage characteristics of non-ohmic components Measuring resistance and resistivity in the laboratory The heating effect of a current and choosing a power equation Thermistors and how a semiconductor's resistance falls with temperature Conductance, conductivity and comparing materials

D.C. Circuits

Topic overview Kirchhoff's laws, and resistors in series and parallel Potential dividers, emf and internal resistance Cells, resistivity, power and energy Working out currents and potential differences in resistor networks Sensor circuits with thermistors and LDRs Internal resistance, power transfer and short-circuit current Ammeters, voltmeters and their effect on the circuit

The Nature of Waves

Topic overview What a wave is, and the wave equation Describing a wave: peaks, compressions and phase Polarisation and plane-polarised waves Displacement–time and displacement–position graphs Wavefronts and rays Phase difference between two points on a wave

Wave Properties

Topic overview Energy transfer and the wave equation Transverse and longitudinal waves, path difference and intensity Diffraction and superposition Two-source interference and the diffraction grating Stationary waves How much a wave spreads at a gap or an obstacle Coherence and the conditions for observable interference Young's double slit and λ = ay/D Measuring wavelength with a diffraction grating Measuring the speed of sound with stationary waves

Refraction of Light

Topic overview What refraction is and why it happens Refractive index and Snell's law Total internal reflection and optical fibres The wave model of refraction and n₁v₁ = n₂v₂ Snell's law at a boundary between two media Optical fibres: core, cladding and pulse broadening

Photons

Topic overview Photon energy and the electronvolt The photoelectric effect Stopping potential and the Planck constant The photoelectric effect and photon energies Line spectra and energy levels Demonstrating the photoelectric effect The electromagnetic spectrum and typical photon energies Electron diffraction and the de Broglie relationship Radiation pressure

Lasers

Topic overview Stimulated emission and the properties of laser light Population inversion, pumping and the laser cavity Why a two-level system cannot give a population inversion Three-level and four-level laser systems The semiconductor laser and its uses

Mathematical Requirements (Appendix C)

Topic overview Significant figures and arithmetic means Uncertainty and how uncertainties combine Algebraic symbols and proportionality Rearranging and solving equations Small angle approximations Tangents and instantaneous rates of change Areas under curves and numerical methods Reading a tangent on a motion graph Straight-line graphs and y = mx + c What a gradient and an intercept represent Linearising a relationship to find a constant Log plots of exponential decay Choosing what to plot to find a constant Logarithmic scales and orders of magnitude Working with base-ten logarithms The shapes of common graphs Inverse and root relationships on a graph Areas, volumes and Pythagoras Geometry applied to physical situations Substituting into physical equations Trigonometry and right-angled triangles Resolving a force into components Radians, arc length and force diagrams Random processes and translating between representations Mean values and periodic functions Symbols for approximation and comparison

How Science Works (Appendix D)

Topic overview Apparatus and taking measurements Working safely with radioactive sources Planning an investigation Analysing and evaluating evidence Uncertainty, repeatability and drawing a conclusion

How Science Works (Appendix D)

5 subtopics
15 things to know
All units

What How Science Works (Appendix D) covers

How Science Works is assessed across every unit of WJEC Physics, and in the unit 5 practical examination. 66 recall questions across 5 subtopics.

Where it is assessed

All units

Assessed throughout, and in the unit 5 practical examination.

Check the WJEC specification ↗

The 5 subtopics

Each one has its own page. WJEC AS Physics students sit this topic in the first year.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

What must be settled before an experiment is carried out?

Key term

What practices are essential for maintaining scientific integrity?

Key term

What types of measurements can be recorded using analogue apparatus, and what technique improves precision when reading scales?

Key term

Name five quantities that can be measured with digital instruments, including electrical multimeters.

Key term

What must be conducted before carrying out experimental work involving radioactive sources?

Process

How does minimising exposure time reduce risk when working with radioactive sources?

Key term

When plotting experimental data on a graph, which variable goes on which axis?

Key term

What determines whether a methodology is appropriate for a scientific investigation?

Key term

Distinguish between a random error and a systematic error.

Key term

Give one example of a random error in a laboratory measurement.

Key term

What instruments can be used for timing in physics experiments?

Key term

Explain why maximising distance from a radioactive source is an effective safety measure.

Key term

When plotting experimental data, which variable is placed on the x-axis?

Key term

What is a correlation between two variables?

Key term

Give one example of a systematic error.

Take How Science Works (Appendix D) further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

A correlation vs A causal relationship
A correlation: two variables changing together, which alone proves nothing about cause. A causal relationship: one in which a change in the first variable directly produces the change in the second.
An independent variable vs A control variable
An independent variable: the quantity the experimenter deliberately changes. A control variable: a quantity deliberately held constant so it cannot affect the result.

Questions from this topic

Each one with the model answer underneath.

1
What types of measurements can be recorded using analogue apparatus, and what technique improves precision when reading scales?
Model answer
Measurements including length/distance, temperature, pressure, force, angles, and volume; precision is improved by interpolating between scale markings.
2
Name five quantities that can be measured with digital instruments, including electrical multimeters.
Model answer
Time, current, voltage, resistance, and mass.
3
State four methods used to increase the accuracy of measurements in experiments.
Model answer
Timing over multiple oscillations, using a fiducial marker, using a set square, or using a plumb line.
4
What instruments can be used for timing in physics experiments?
Model answer
A stopwatch or light gates.
5
What instruments are used to measure small distances, and what types of scales might they have?
Model answer
Callipers and micrometers, which may have digital or vernier scales.
6
When constructing circuits from circuit diagrams, what must be considered for certain components?
Model answer
Polarity must be considered for components where it is important (such as diodes, LEDs, and electrolytic capacitors).

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How Science Works (Appendix D) revision questions

Is How Science Works (Appendix D) examined at AS in WJEC Physics?: Yes. It sits in All units, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
What does How Science Works (Appendix D) cover in WJEC AS-Level Physics?: 5 subtopics: apparatus and taking measurements, working safely with radioactive sources, planning an investigation, analysing and evaluating evidence and uncertainty, repeatability and drawing a conclusion. Each one has its own page with questions and model answers.
How is How Science Works (Appendix D) organised?: By the WJEC 1420QS specification, subtopic by subtopic, so it matches the order you are taught it in.

Every question in How Science Works (Appendix D), on a schedule.

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