10.1.4
Correcting Defects of Vision
Astigmatism Prescriptions
Astigmatism Prescriptions
A prescription for astigmatism contains three terms: S, C and A.
S
S
- The 'spherical' part of the prescription in dioptres, ie the short or long sightedness correction.
C
C
- The degree of astigmatism, also measured in dioptres.
A
A
- The orientation of astigmatism from 0 to 180 degrees.
Example prescriptions
Example prescriptions
- E.g. -2.00 +1.50 × 180
- E.g. +3.50 +3.00 × 45
1Measurements & Errors
2Particles & Radiation
2.1Particles
2.1.1Atomic Model
2.1.2Specific Charge, Protons & Neutron Numbers
2.1.3End of Topic Test - Atomic Model
2.1.4Isotopes
2.1.5Stable & Unstable Nuclei
2.1.6End of Topic Test - Isotopes & Nuclei
2.1.7A-A* (AO3/4) - Stable & Unstable Nuclei
2.1.8Particles, Antiparticles & Photons
2.1.9Particle Interactions
2.1.10Classification of Particles
2.1.11End of Topic Test - Particles & Interactions
2.1.12Quarks & Antiquarks
2.1.13Application of Conservation Laws
2.1.14End of Topic Test - Leptons & Quarks
2.1.15Exam-Style Question - Radioactive Decay
2.2Electromagnetic Radiation & Quantum Phenomena
3Waves
3.1Progressive & Stationary Waves
3.2Refraction, Diffraction & Interference
4Mechanics & Materials
4.1Force, Energy & Momentum
4.1.1Scalars & Vectors
4.1.2Vector Problems
4.1.3End of Topic Test - Scalars & Vectors
4.1.4Moments
4.1.5Centre of Mass
4.1.6End of Topic Test - Moments & Centre of Mass
4.1.7Motion in a Straight Line
4.1.8Graphs of Motion
4.1.9Bouncing Ball Example
4.1.10End of Topic Test - Motion in a Straight Line
4.1.11Acceleration Due to Gravity
4.1.12Projectile Motion
4.1.13Friction
4.1.14Terminal Speed
4.1.15End of Topic Test - Acceleration Due to Gravity
4.1.16Newton's Laws
4.1.17Momentum
4.1.18Momentum 2
4.1.19End of Topic Test - Newton's Laws & Momentum
4.1.20A-A* (AO3/4) - Newton's Third Law
4.1.21Work & Energy
4.1.22Power & Efficiency
4.1.23Conservation of Energy
4.1.24End of Topic Test - Work, Energy & Power
4.1.25Exam-Style Question - Forces
5Electricity
5.1Current Electricity
5.1.1Basics of Electricity
5.1.2Current-Voltage Characteristics
5.1.3End of Topic Test - Basics of Electricity
5.1.4Resistivity
5.1.5Superconductivity
5.1.6A-A* (AO3/4) - Superconductivity
5.1.7End of Topic Test - Resistivity & Superconductors
5.1.8Circuits
5.1.9Power and Conservation
5.1.10Potential Divider
5.1.11Emf & Internal Resistance
5.1.12End of Topic Test - Power & Potential
5.1.13Exam-Style Question - Resistance
6Further Mechanics & Thermal Physics (A2 only)
6.1Periodic Motion (A2 only)
6.2Thermal Physics (A2 only)
7Fields & Their Consequences (A2 only)
7.1Fields (A2 only)
7.2Gravitational Fields (A2 only)
7.3Electric Fields (A2 only)
7.4Capacitance (A2 only)
7.5Magnetic Fields (A2 only)
7.5.1Magnetic Flux Density
7.5.2End of Topic Test - Capacitance & Flux Density
7.5.3Moving Charges in a Magnetic Field
7.5.4Magnetic Flux & Flux Linkage
7.5.5Electromagnetic Induction
7.5.6Electromagnetic Induction 2
7.5.7Alternating Currents
7.5.8Operation of a Transformer
7.5.9Magnetic Flux Density
7.5.10End of Topic Test - Electromagnetic Induction
8Nuclear Physics (A2 only)
8.1Radioactivity (A2 only)
8.1.1Rutherford Scattering
8.1.2Alpha & Beta Radiation
8.1.3Gamma Radiation
8.1.4Radioactive Decay
8.1.5Half Life
8.1.6End of Topic Test - Radioactivity
8.1.7Nuclear Instability
8.1.8Nuclear Radius
8.1.9Mass & Energy
8.1.10Binding Energy
8.1.11Induced Fission
8.1.12Safety Aspects of Nuclear Reactors
8.1.13End of Topic Test - Nuclear Physics
8.1.14A-A* (AO3/4) - Nuclear Fusion
9Option: Astrophysics (A2 only)
9.1Telescopes (A2 only)
9.2Classification of Stars (A2 only)
9.3Cosmology (A2 only)
10Option: Medical Physics (A2 only)
10.1Physics of the Eye (A2 only)
10.2Physics of the Ear (A2 only)
10.3Biological Measurement (A2 only)
10.4Non-Ionising Imaging (A2 only)
10.5X-Ray Imaging (A2 only)
10.6Radionuclide Imaging & Therapy (A2 only)
11Option: Engineering Physics (A2 only)
11.1Rotational Dynamics (A2 only)
11.2Thermodynamics & Engines (A2 only)
12Option: Turning Points in Physics (A2 only)
12.1Discovery of the Electron (A2 only)
12.2Wave-Particle Duality (A2 only)
Jump to other topics
1Measurements & Errors
2Particles & Radiation
2.1Particles
2.1.1Atomic Model
2.1.2Specific Charge, Protons & Neutron Numbers
2.1.3End of Topic Test - Atomic Model
2.1.4Isotopes
2.1.5Stable & Unstable Nuclei
2.1.6End of Topic Test - Isotopes & Nuclei
2.1.7A-A* (AO3/4) - Stable & Unstable Nuclei
2.1.8Particles, Antiparticles & Photons
2.1.9Particle Interactions
2.1.10Classification of Particles
2.1.11End of Topic Test - Particles & Interactions
2.1.12Quarks & Antiquarks
2.1.13Application of Conservation Laws
2.1.14End of Topic Test - Leptons & Quarks
2.1.15Exam-Style Question - Radioactive Decay
2.2Electromagnetic Radiation & Quantum Phenomena
3Waves
3.1Progressive & Stationary Waves
3.2Refraction, Diffraction & Interference
4Mechanics & Materials
4.1Force, Energy & Momentum
4.1.1Scalars & Vectors
4.1.2Vector Problems
4.1.3End of Topic Test - Scalars & Vectors
4.1.4Moments
4.1.5Centre of Mass
4.1.6End of Topic Test - Moments & Centre of Mass
4.1.7Motion in a Straight Line
4.1.8Graphs of Motion
4.1.9Bouncing Ball Example
4.1.10End of Topic Test - Motion in a Straight Line
4.1.11Acceleration Due to Gravity
4.1.12Projectile Motion
4.1.13Friction
4.1.14Terminal Speed
4.1.15End of Topic Test - Acceleration Due to Gravity
4.1.16Newton's Laws
4.1.17Momentum
4.1.18Momentum 2
4.1.19End of Topic Test - Newton's Laws & Momentum
4.1.20A-A* (AO3/4) - Newton's Third Law
4.1.21Work & Energy
4.1.22Power & Efficiency
4.1.23Conservation of Energy
4.1.24End of Topic Test - Work, Energy & Power
4.1.25Exam-Style Question - Forces
5Electricity
5.1Current Electricity
5.1.1Basics of Electricity
5.1.2Current-Voltage Characteristics
5.1.3End of Topic Test - Basics of Electricity
5.1.4Resistivity
5.1.5Superconductivity
5.1.6A-A* (AO3/4) - Superconductivity
5.1.7End of Topic Test - Resistivity & Superconductors
5.1.8Circuits
5.1.9Power and Conservation
5.1.10Potential Divider
5.1.11Emf & Internal Resistance
5.1.12End of Topic Test - Power & Potential
5.1.13Exam-Style Question - Resistance
6Further Mechanics & Thermal Physics (A2 only)
6.1Periodic Motion (A2 only)
6.2Thermal Physics (A2 only)
7Fields & Their Consequences (A2 only)
7.1Fields (A2 only)
7.2Gravitational Fields (A2 only)
7.3Electric Fields (A2 only)
7.4Capacitance (A2 only)
7.5Magnetic Fields (A2 only)
7.5.1Magnetic Flux Density
7.5.2End of Topic Test - Capacitance & Flux Density
7.5.3Moving Charges in a Magnetic Field
7.5.4Magnetic Flux & Flux Linkage
7.5.5Electromagnetic Induction
7.5.6Electromagnetic Induction 2
7.5.7Alternating Currents
7.5.8Operation of a Transformer
7.5.9Magnetic Flux Density
7.5.10End of Topic Test - Electromagnetic Induction
8Nuclear Physics (A2 only)
8.1Radioactivity (A2 only)
8.1.1Rutherford Scattering
8.1.2Alpha & Beta Radiation
8.1.3Gamma Radiation
8.1.4Radioactive Decay
8.1.5Half Life
8.1.6End of Topic Test - Radioactivity
8.1.7Nuclear Instability
8.1.8Nuclear Radius
8.1.9Mass & Energy
8.1.10Binding Energy
8.1.11Induced Fission
8.1.12Safety Aspects of Nuclear Reactors
8.1.13End of Topic Test - Nuclear Physics
8.1.14A-A* (AO3/4) - Nuclear Fusion
9Option: Astrophysics (A2 only)
9.1Telescopes (A2 only)
9.2Classification of Stars (A2 only)
9.3Cosmology (A2 only)
10Option: Medical Physics (A2 only)
10.1Physics of the Eye (A2 only)
10.2Physics of the Ear (A2 only)
10.3Biological Measurement (A2 only)
10.4Non-Ionising Imaging (A2 only)
10.5X-Ray Imaging (A2 only)
10.6Radionuclide Imaging & Therapy (A2 only)
11Option: Engineering Physics (A2 only)
11.1Rotational Dynamics (A2 only)
11.2Thermodynamics & Engines (A2 only)
12Option: Turning Points in Physics (A2 only)
12.1Discovery of the Electron (A2 only)
12.2Wave-Particle Duality (A2 only)
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