3.2.2
Interference 2
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Laser Safety
Lasers are dangerous and need careful handling and use.

Laser safety
- To be safe with lasers you should:
- Not point the laser in people's eyes.
- Wear protective clothing and eyewear as necessary.
- Make sure that internationally agreed signage is used outside and inside laboratories.
- Stick to institutional safety requirements.

Danger of lasers
- We need to be safe with lasers because they are highly luminous over a very small area.
- The major risk with lasers is eye injury.
- With high powered lasers, the body's natural aversion reflex (the eye will automatically look away from a bright source) is too slow to prevent damage to the retina.
Understanding EM Radiation
Scientists have changed and updated their understanding of the nature of electromagnetic radiation over time. Newton, Huygens, Young and Einstein are prominent scientists in the theory of light.

Newton's corpuscles
- In the 1600s Isaac Newton theorised light as made up of "corpuscles", little packets of light.

Huygens' waves
- Huygens stated his wavefront theory in the 1600s.

Young's double slit experiment
- Young, with his double-slit experiment, provided evidence of Huygens' wavefront principle.

Einstein's photons
- Einstein provided evidence, through the photoelectric effect, supporting Newton's corpuscular theory.
- This was the beginnings of quantum theory.

Compton's scattering experiment
- Further on in the 20th century, Compton scattering (a photon scattering off an electron) provided more evidence for the quantisation of light.
Interference of Sound Waves
Interference can be observed in all types of waves, including sound waves.

Experimental set up
- To observe interference in sound waves, we can use the above set up.
- The two sources need to be coherent, meaning that the same sound must be played at the same time in each speaker.

Move microphone
- By moving the microphone from one side to the other, we can measure constructive and destructive interference by whether the noise is loud or quiet.
1Measurements & Errors
1.1Measurements & Errors
1.1.1SI Base Units1.1.2Combining SI Units1.1.3Prefixes of Units1.1.4Standard Form1.1.5Converting Units1.1.6End of Topic Test - Units & Prefixes1.1.7Limitation of Physical Measurements1.1.8Uncertainty1.1.9Estimation1.1.10End of Topic Test - Measurements & Errors1.1.11Diagnostic Misconceptions - Converting between SI1.1.12Diagnostic Misconceptions - SI & Area/Volume
2Particles & Radiation
2.1Particles
2.1.1Atomic Model2.1.2Specific Charge, Protons & Neutron Numbers2.1.3End of Topic Test - Atomic Model2.1.4Isotopes2.1.5Stable & Unstable Nuclei2.1.6End of Topic Test - Isotopes & Nuclei2.1.7A-A* (AO3/4) - Stable & Unstable Nuclei2.1.8Particles, Antiparticles & Photons2.1.9Particle Interactions2.1.10Classification of Particles2.1.11End of Topic Test - Particles & Interactions2.1.12Quarks & Antiquarks2.1.13Application of Conservation Laws2.1.14End of Topic Test - Leptons & Quarks2.1.15Exam-Style Question - Radioactive Decay
2.2Electromagnetic Radiation & Quantum Phenomena
2.2.1The Photoelectric Effect2.2.2The Photoelectric Effect Explanation2.2.3End of Topic Test - The Photoelectric Effect2.2.4Collisions of Electrons with Atoms2.2.5Energy Levels & Photon Emission2.2.6Wave-Particle Duality2.2.7End of Topic Test - Absorption & Emission2.2.8Diagnostic Misconceptions - Electron Volts2.2.9Diagnostic Misconceptions - Converting eV & Joules
3Waves
3.1Progressive & Stationary Waves
3.2Refraction, Diffraction & Interference
4Mechanics & Materials
4.1Force, Energy & Momentum
4.1.1Scalars & Vectors4.1.2Vector Problems4.1.3End of Topic Test - Scalars & Vectors4.1.4Moments4.1.5Centre of Mass4.1.6End of Topic Test - Moments & Centre of Mass4.1.7Motion in a Straight Line4.1.8Graphs of Motion4.1.9Bouncing Ball Example4.1.10End of Topic Test - Motion in a Straight Line4.1.11Acceleration Due to Gravity4.1.12Projectile Motion4.1.13Friction4.1.14Terminal Speed4.1.15End of Topic Test - Acceleration Due to Gravity4.1.16Newton's Laws4.1.17Momentum4.1.18Momentum 24.1.19End of Topic Test - Newton's Laws & Momentum4.1.20A-A* (AO3/4) - Newton's Third Law4.1.21Work & Energy4.1.22Power & Efficiency4.1.23Conservation of Energy4.1.24End of Topic Test - Work, Energy & Power4.1.25Exam-Style Question - Forces4.1.26Diagnostic Misconceptions - Perpendicular Vectors4.1.27Diagnostic Misconceptions - Weight Acts Downwards4.1.28Diagnostic Misconceptions - Acceleration Direction4.1.29Diagnostic Misconceptions - Stationary Objects4.1.30Diagnostic Misconceptions - Action & Reaction4.1.31Diagnostic Misconceptions - RF Direction4.1.32Diagnostic Misconceptions - RF Acceleration4.1.33Diagnostic Misconceptions - Change in Momentum
5Electricity
5.1Current Electricity
5.1.1Basics of Electricity5.1.2Current-Voltage Characteristics5.1.3End of Topic Test - Basics of Electricity5.1.4Resistivity5.1.5Superconductivity5.1.6A-A* (AO3/4) - Superconductivity5.1.7End of Topic Test - Resistivity & Superconductors5.1.8Circuits5.1.9Power and Conservation5.1.10Potential Divider5.1.11Emf & Internal Resistance5.1.12End of Topic Test - Power & Potential5.1.13Exam-Style Question - Resistance5.1.14Diagnostic Misconceptions - Constant Current5.1.15Diagnostic Misconceptions - Potential Difference
6Further Mechanics & Thermal Physics (A2 only)
6.1Periodic Motion (A2 only)
6.2Thermal Physics (A2 only)
6.2.1Thermal Energy Transfer6.2.2Thermal Energy Transfer Experiments6.2.3Ideal Gases6.2.4Ideal Gases 26.2.5Boyle's Law & Charles' Law6.2.6Molecular Kinetic Theory Model6.2.7Molecular Kinetic Theory Model 26.2.8End of Topic Test - Thermal Energy & Ideal Gases6.2.9Exam-Style Question - Ideal Gases6.2.10Diagnostic Misconceptions - Material & Mass6.2.11Diagnostic Misconceptions - No Energy
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 Density7.5.2End of Topic Test - Capacitance & Flux Density7.5.3Moving Charges in a Magnetic Field7.5.4Magnetic Flux & Flux Linkage7.5.5Electromagnetic Induction7.5.6Electromagnetic Induction 27.5.7Alternating Currents7.5.8Operation of a Transformer7.5.9Magnetic Flux Density7.5.10End of Topic Test - Electromagnetic Induction
8Nuclear Physics (A2 only)
8.1Radioactivity (A2 only)
8.1.1Rutherford Scattering8.1.2Alpha & Beta Radiation8.1.3Gamma Radiation8.1.4Radioactive Decay8.1.5Half Life8.1.6End of Topic Test - Radioactivity8.1.7Nuclear Instability8.1.8Nuclear Radius8.1.9Mass & Energy8.1.10Binding Energy8.1.11Induced Fission8.1.12Safety Aspects of Nuclear Reactors8.1.13End of Topic Test - Nuclear Physics8.1.14A-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
1.1Measurements & Errors
1.1.1SI Base Units1.1.2Combining SI Units1.1.3Prefixes of Units1.1.4Standard Form1.1.5Converting Units1.1.6End of Topic Test - Units & Prefixes1.1.7Limitation of Physical Measurements1.1.8Uncertainty1.1.9Estimation1.1.10End of Topic Test - Measurements & Errors1.1.11Diagnostic Misconceptions - Converting between SI1.1.12Diagnostic Misconceptions - SI & Area/Volume
2Particles & Radiation
2.1Particles
2.1.1Atomic Model2.1.2Specific Charge, Protons & Neutron Numbers2.1.3End of Topic Test - Atomic Model2.1.4Isotopes2.1.5Stable & Unstable Nuclei2.1.6End of Topic Test - Isotopes & Nuclei2.1.7A-A* (AO3/4) - Stable & Unstable Nuclei2.1.8Particles, Antiparticles & Photons2.1.9Particle Interactions2.1.10Classification of Particles2.1.11End of Topic Test - Particles & Interactions2.1.12Quarks & Antiquarks2.1.13Application of Conservation Laws2.1.14End of Topic Test - Leptons & Quarks2.1.15Exam-Style Question - Radioactive Decay
2.2Electromagnetic Radiation & Quantum Phenomena
2.2.1The Photoelectric Effect2.2.2The Photoelectric Effect Explanation2.2.3End of Topic Test - The Photoelectric Effect2.2.4Collisions of Electrons with Atoms2.2.5Energy Levels & Photon Emission2.2.6Wave-Particle Duality2.2.7End of Topic Test - Absorption & Emission2.2.8Diagnostic Misconceptions - Electron Volts2.2.9Diagnostic Misconceptions - Converting eV & Joules
3Waves
3.1Progressive & Stationary Waves
3.2Refraction, Diffraction & Interference
4Mechanics & Materials
4.1Force, Energy & Momentum
4.1.1Scalars & Vectors4.1.2Vector Problems4.1.3End of Topic Test - Scalars & Vectors4.1.4Moments4.1.5Centre of Mass4.1.6End of Topic Test - Moments & Centre of Mass4.1.7Motion in a Straight Line4.1.8Graphs of Motion4.1.9Bouncing Ball Example4.1.10End of Topic Test - Motion in a Straight Line4.1.11Acceleration Due to Gravity4.1.12Projectile Motion4.1.13Friction4.1.14Terminal Speed4.1.15End of Topic Test - Acceleration Due to Gravity4.1.16Newton's Laws4.1.17Momentum4.1.18Momentum 24.1.19End of Topic Test - Newton's Laws & Momentum4.1.20A-A* (AO3/4) - Newton's Third Law4.1.21Work & Energy4.1.22Power & Efficiency4.1.23Conservation of Energy4.1.24End of Topic Test - Work, Energy & Power4.1.25Exam-Style Question - Forces4.1.26Diagnostic Misconceptions - Perpendicular Vectors4.1.27Diagnostic Misconceptions - Weight Acts Downwards4.1.28Diagnostic Misconceptions - Acceleration Direction4.1.29Diagnostic Misconceptions - Stationary Objects4.1.30Diagnostic Misconceptions - Action & Reaction4.1.31Diagnostic Misconceptions - RF Direction4.1.32Diagnostic Misconceptions - RF Acceleration4.1.33Diagnostic Misconceptions - Change in Momentum
5Electricity
5.1Current Electricity
5.1.1Basics of Electricity5.1.2Current-Voltage Characteristics5.1.3End of Topic Test - Basics of Electricity5.1.4Resistivity5.1.5Superconductivity5.1.6A-A* (AO3/4) - Superconductivity5.1.7End of Topic Test - Resistivity & Superconductors5.1.8Circuits5.1.9Power and Conservation5.1.10Potential Divider5.1.11Emf & Internal Resistance5.1.12End of Topic Test - Power & Potential5.1.13Exam-Style Question - Resistance5.1.14Diagnostic Misconceptions - Constant Current5.1.15Diagnostic Misconceptions - Potential Difference
6Further Mechanics & Thermal Physics (A2 only)
6.1Periodic Motion (A2 only)
6.2Thermal Physics (A2 only)
6.2.1Thermal Energy Transfer6.2.2Thermal Energy Transfer Experiments6.2.3Ideal Gases6.2.4Ideal Gases 26.2.5Boyle's Law & Charles' Law6.2.6Molecular Kinetic Theory Model6.2.7Molecular Kinetic Theory Model 26.2.8End of Topic Test - Thermal Energy & Ideal Gases6.2.9Exam-Style Question - Ideal Gases6.2.10Diagnostic Misconceptions - Material & Mass6.2.11Diagnostic Misconceptions - No Energy
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 Density7.5.2End of Topic Test - Capacitance & Flux Density7.5.3Moving Charges in a Magnetic Field7.5.4Magnetic Flux & Flux Linkage7.5.5Electromagnetic Induction7.5.6Electromagnetic Induction 27.5.7Alternating Currents7.5.8Operation of a Transformer7.5.9Magnetic Flux Density7.5.10End of Topic Test - Electromagnetic Induction
8Nuclear Physics (A2 only)
8.1Radioactivity (A2 only)
8.1.1Rutherford Scattering8.1.2Alpha & Beta Radiation8.1.3Gamma Radiation8.1.4Radioactive Decay8.1.5Half Life8.1.6End of Topic Test - Radioactivity8.1.7Nuclear Instability8.1.8Nuclear Radius8.1.9Mass & Energy8.1.10Binding Energy8.1.11Induced Fission8.1.12Safety Aspects of Nuclear Reactors8.1.13End of Topic Test - Nuclear Physics8.1.14A-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)
Practice questions on Interference 2
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Laser safety requirements:Fill in the list
- 2Which of these must you do when using lasers?True / false
- 3History of EM RadiationPut in order
- 4
- 5
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