6.2.1

Waves at a Boundary

Test yourself

Waves at a Boundary

When waves travel from one medium to another, their speed and wavelength change but their frequency stays the same.

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Speed and wavelength change

  • The speed of a wave changes when it travels from one medium to another.
  • The wavelength of a wave also changes when it travels from one medium to another.
  • The speed and the wavelength are directly proportional:
    • If the speed doubles, the wavelength doubles.
    • If the speed halves, the wavelength halves.
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Frequency is unchanged

  • The frequency of the wave does not change because the source is producing the same number of oscillations (vibrations) per second.

Waves at a Boundary

Waves can be reflected, refracted, absorbed and transmitted (passes through) at the boundary between one medium (material) and another.

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Refraction

  • A wave’s speed can change when moving from one medium to another.
  • If the wave crosses to the new medium at an angle (not 90 degrees), the change in the wave’s speed will cause the direction of the wave’s motion to change and the wave will appear to bend.
  • This is called refraction.
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Reflection

  • Reflection happens when a wave hits a flat surface (plane) and bounces off.
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Absorption

  • When waves meet some materials, the energy is absorbed by the material.
  • For example, when light falls on a matt black surface, most of the energy is absorbed.
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Transmission

  • Waves carry on travelling through a new material.
  • This often leads to refraction.

Reflection of Light

Light can be reflected by a plane (flat surface).

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Angle of incidence

  • The angle of incidence is the angle between the incident (incoming) light ray and the normal.
  • The normal is a line at 90 degrees to the plane.
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Angle of reflection

  • The angle of reflection is the angle between the reflected light ray and the normal.
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Law of reflection

  • The law of reflection states that the angle of incidence = the angle of reflection.

Jump to other topics

1Energy

1.1Energy Changes

1.1.1Energy Stores

1.1.2Calculating Changes in Energy

1.1.3Changes in Kinetic Energy - Calculations

1.1.4Changes in GPE - Calculations

1.1.5Changes in EPE - Calculations

1.1.6Energy Transfers

1.1.7Mechanical Work Done

1.1.8Mechanical Work - Calculations

1.1.9Electrical Work Done

1.1.10Electrical Work Done- Calculations

1.2Energy Losses & Efficiency

1.2.1Energy Losses & Efficiency

1.2.2Energy Losses & Efficiency 2

1.2.3Efficiency - Calculations

1.2.4Grade 9 - Energy & Efficiency

1.3Energy Resources

1.3.1Fossil Fuels & Geothermal Energy

1.3.2Wind & Water Energy Sources

1.3.3Nuclear & Solar Energy

1.3.4Sustainability

1.3.5Renewable Energy

1.3.6End of Topic Test - Energy

1.3.7Exam-Style Questions - Energy

2Electricity

2.1Electric Charge

2.1.1Circuit Diagrams & Components

2.1.2Current

2.1.3Current - Calculations

2.1.4Conductors

2.1.5Potential Difference

2.1.6Voltage - Calculations

2.2Resistance & Electrical Work

2.2.1Resistance

2.2.2Diodes, LDRs & Thermistors

2.2.3Electrical Work

2.2.4Ohm's Law

2.2.5Resistance and Ohms Law - Calculations

2.2.6Electrical Work - Calculations

2.3Electric Circuits

2.3.1Series Circuits

2.3.2Series Circuits 2

2.3.3Series Circuits - Calculations

2.3.4Parallel Circuits

2.3.5Parallel Circuits 2

2.3.6Parallel Circuits - Calculations

2.3.7Grade 9 - Circuits

2.3.8Exam-Style Questions - Electricity

2.4Electricity in Homes

2.4.1Domestic Uses

2.4.2Domestic Uses 2

2.4.3Domestic Uses - Calculations

2.4.4Electrical Safety

2.4.5Electrical Safety 2

2.4.6End of Topic Test - Electricity

2.5Static Electricity

2.5.1Static Electricity

2.5.2Static Electricity 2

3Particle Model of Matter

3.1States of Matter

3.1.1Atomic Structure

3.1.2Atomic Structure 2

3.1.3Density

3.1.4Density - Calculations

3.1.5Changes of State

3.1.6Exam-Style Questions - Density

3.2Heat

3.2.1Internal Energy

3.2.2Heat Capacities

3.2.3Internal Energy - Calculations

3.2.4Latent Heat

3.2.5Latent Heat - Calculations

3.2.6Latent Heat Experiments

3.3Particle Motion in Gases

3.3.1Particle Motion in Gases

3.3.2Particle Motion in Gases 2

3.3.3End of Topic Test - Particle Model of Matter

3.3.4Grade 9 - Particle Model of Matter

3.3.5Exam-Style Questions - Specific Heat Capacity

4Atoms & Radiation

4.1Atoms

4.1.1Atomic Model

4.1.2Atomic Model 2

4.1.3Atoms & Ions

4.1.4Isotopes

4.1.5Exam-Style Questions - Atomic Structure

4.2Radiation

4.2.1Radioactive Decay

4.2.2Radioactive Decay 2

4.2.3Types of Radioactive Emission

4.2.4Fission & Fusion

4.2.5Radioactive Decay Equations

4.2.6Radio. decay equations - Calculations

4.2.7Half Lives & Ionising Radiation

4.2.8Half Life - Calculations

4.2.9Uses & Dangers of Radiation

4.2.10Uses & Dangers of Radiation 2

4.2.11End of Topic Test - Atoms & Radiation

4.2.12Grade 9 - Radiation

4.2.13Exam-Style Questions - Radioactive Decay

5Forces

5.1Basics of Motion

5.1.1Basics of Motion

5.1.2Basics of Motion 2

5.1.3Basics of Motion 3

5.1.4Distance- & Speed-Time Graphs

5.1.5Average Speed - Calculations

5.1.6Acceleration - Calculations

5.1.7Uniform Acceleration - Calculations

5.1.8Grade 9 - Motion

5.1.9Exam-Style Questions - Motion

5.2Forces

5.2.1Gravity

5.2.2Gravity - Calculations

5.2.3Resultant Forces

5.2.4Newton Second Law - Calculations

5.2.5Force Diagrams

5.2.6Free Body Diagrams - Calculations

5.2.7Stretching a Spring

5.2.8Hooke's Law

5.2.9Hooke's Law - Calculations

5.2.10Elastic Potential Energy

5.2.11Elastic Potential - Calculations

5.2.12Exam-Style Questions - Elastic Potential Energy

5.3Effects of Forces

5.3.1Acceleration

5.3.2Acceleration 2

5.3.3Momentum

5.3.4Change in Momentum - Calculations

5.3.5Momentum - Calculations

5.3.6Moments

5.3.7Moments - Calculations

5.3.8Circular Motion

5.3.9Levers & Gears

5.3.10Stopping Distance

5.3.11Decelerations

5.3.12Stopping Distance - Calculations

5.4Pressure

5.4.1Pressure

5.4.2Pressure - Calculations

5.4.3Liquid Pressure - Calculations

5.4.4Pressure Changes

5.4.5End of Topic Test - Forces

5.4.6Exam-Style Questions - Pressure

6Waves

6.1Wave Basics

6.1.1Basics & Formula

6.1.2Wave Speed - Calculations

6.1.3Describing Waves

6.1.4Wave Frequency - Calculations

6.1.5Transverse & Longitudinal Waves

6.1.6Required Practical - Ripple Tank

6.2Waves at a Boundary

6.2.1Waves at a Boundary

6.2.2Waves at a Boundary 2

6.3Sound Waves

6.3.1Sound Waves

6.3.2Sound Waves 2

6.3.3Uses of Sound Waves

6.3.4Sound Waves - Calculations

6.3.5End of Topic Test - Introduction to Waves

6.3.6Exam-Style Questions - Wave Speed

6.4Electromagnetic Waves

6.4.1Properties

6.4.2Gamma, X-Ray & UV Light

6.4.3Infrared, Microwave & Radio Waves

6.4.4Properties 2

6.4.5Visible Light

6.4.6Visible Light 2

6.4.7Grade 9 - Waves

6.5Lenses

6.5.1Lenses

6.5.2Lenses - Calculations

6.5.3Images & Ray Diagrams

6.6Heat & Radiation

6.6.1Infrared Radiation

6.6.2Temperature

6.6.3Greenhouse Effect

6.6.4End of Topic Test - EM Waves, Lenses & Heat

6.6.5Exam-Style Questions - EM Radiation

7Magnetism

7.1Magnetism Basics

7.1.1Magnetic Materials

7.1.2Magnetic Fields

7.2Electromagnetism

7.2.1Electromagnetism

7.2.2Electromagnetism 2

7.2.3Motor Effect

7.2.4Magnetic Flux - Calculations

7.2.5Motors

7.2.6Induced Potential

7.2.7Induced Potential 2

7.2.8Generator Effect

7.2.9Generator Effect 2

7.3Transformers

7.3.1Transformers

7.3.2Transformers 2

7.3.3Transformers 3

7.3.4Transformers - Calculations

7.3.5Transformers 2 - Calculations

7.3.6End of Topic Test - Magnetism

7.3.7Grade 9 - Transformers

7.3.8Exam-Style Questions - Magnetic Fields

8Astrophysics

8.1Astrophysics

8.1.1The Solar System

8.1.2The Solar System - Calculations

8.1.3Orbits

8.1.4Orbits HyperLearning

8.1.5Life Cycle of a Star

8.1.6The Universe

8.1.7End of Topic Test - Astrophysics

8.1.8Exam-Style Questions - Astrophysics

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Required Practical - Ripple Tank

Waves at a Boundary 2