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    Chapter 3 IGCSE

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    Najia Umar
    This document provides information about properties of waves including light and sound. It defines key wave terms like amplitude, wavelength, period, and frequency. It describes the properties and behaviors of different types of waves such as transverse waves, longitudinal waves, reflection, refraction, and diffraction. Specific details are given about the nature and behavior of light waves, including reflection, refraction through lenses and prisms, dispersion, and the electromagnetic spectrum. The document also discusses the properties of sound waves, how they propagate through different mediums, and the differences between pitch and loudness.

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    Chapter 3 IGCSE

    Uploaded by

    Najia Umar
    18 views8 pages
    This document provides information about properties of waves including light and sound. It defines key wave terms like amplitude, wavelength, period, and frequency. It describes the properties and behaviors of different types of waves such as transverse waves, longitudinal waves, reflection, refraction, and diffraction. Specific details are given about the nature and behavior of light waves, including reflection, refraction through lenses and prisms, dispersion, and the electromagnetic spectrum. The document also discusses the properties of sound waves, how they propagate through different mediums, and the differences between pitch and loudness.

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    This document provides information about properties of waves including light and sound. It defines key wave terms like amplitude, wavelength, period, and frequency. It describes the properties and behaviors of different types of waves such as transverse waves, longitudinal waves, reflection, refraction, and diffraction. Specific details are given about the nature and behavior of light waves, including reflection, refraction through lenses and prisms, dispersion, and the electromagnetic spectrum. The document also discusses the properties of sound waves, how they propagate through different mediums, and the differences between pitch and loudness.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    18 views8 pages

    Chapter 3 IGCSE

    Uploaded by

    Najia Umar
    This document provides information about properties of waves including light and sound. It defines key wave terms like amplitude, wavelength, period, and frequency. It describes the properties and behaviors of different types of waves such as transverse waves, longitudinal waves, reflection, refraction, and diffraction. Specific details are given about the nature and behavior of light waves, including reflection, refraction through lenses and prisms, dispersion, and the electromagnetic spectrum. The document also discusses the properties of sound waves, how they propagate through different mediums, and the differences between pitch and loudness.

    Copyright:

    © All Rights Reserved
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    of 8

    IGCSE MY NOTES Revision:

    Chapter 3 Properties of Waves, Including Light and Sound


    Prepared by: Chern Jiek Lee 1kHz = Hz
    1MHz = Hz
    3.1 What is a Wave? 1GHz = Hz

    Tick below which you think are waves. Question 1:

    If a wave starts from 0


    meters and then moves up
    and down sinusoidally 5
    times in 1 second. What is
    the period of the wave?
    What is the frequency of the
    wave? Hint: Draw the wave
    out first!

    Ans:

    Transverse waves: Particles vibrate perpendicular/ along the lines of


    motion and consists of a series of “peaks” and “valleys”.

    Longitudinal waves: Particles vibrate perpendicular/ along the lines of


    motion and consists of a series of compression and expansion.
    Wave Language Graph 2 Displacement-Time

    Displacement

    Time

    Amplitude, A: The maximum displacement from the original position. The


    SI unit for amplitude is in meters.

    Wavelength, λ: The horizontal distance between two points that are in


    phase. The SI unit for amplitude is in
    .

    Period, T: Time taken for the wave to complete a cycle or return to its
    original displacement. The SI unit for periods is seconds.

    Frequency, f: The number of complete cycle’s in a second (How many


    times did the wave go up, down and up again or down, up, and down again
    in 1 second). The SI unit for frequency is hertz (Hz) OR seconds-1.

    Hence, relationship between frequency and period is

    1
    𝑓=
    𝑇

    How to “Draw” Waves and What Information can We Derive from


    Them

    Graph 1 Displacement-Distance

    Displacement

    Distance

    Can we find the period of the wave from the D-D graph directly?

    Can we find the wavelength of the wave from the D-T graph directly?
    A wave can undergo this 3 phenomena:
    Reflection, Refraction, Diffraction

    Reflection: Change of direction when it collides with a reflective barrier.

    Refraction: Change of direction when it goes through a change of medium.


    Eg. Water waves change direction when there is a change in the speed of
    the water. The speed of the water changes when there is a change in the
    depth of the water. From deep to shallow waters the wave’s speed increases/
    decreases as the wavelength becomes shorter. From shallow to deep waters
    the wave’s speed increases/ decreases as the wavelength becomes longer
    (Hint: recall v = fλ). Refraction occurs when the direction of motion is not
    perpendicular to border between the deep and shallow regions. Eg. tsunami

    Hint: 1) Draw a line representing the direction of the wave


    propagation.
    2) Draw the normal line.

    Deeper

    Diffraction: Spreads when it passes through an opening or an edge.


    Diffraction increases when the size of the gap decreases or the wavelength
    of the waves increases. Eg. Sea coves
    Wave equation:

    Speed (m/s) = Frequency (Hz) x Wavelength (m)


    v=fxλ

    3.2 Light

    Light is a wave because it undergoes the same 3 phenomenon that waves go


    through

    Reflection

    i=r

    Types of mirror

    Reflection in plane mirror

    The image form is


    1) Upright
    2) Virtual
    3) Laterally inverted
    4) Same size as object
    Refraction

    Refraction is the bending of light ray at the boundary of two medium as the
    light ray propagates from a medium to another with different density.

    When light passes through a medium which is denser


    i>r

    When light passes through a medium which is less dense


    i<r

    Snell’s law states that the value of (sin i) / (sin r) is constant for light
    passing from one given medium into another

    sin 𝑖
    = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡, 𝑛
    sin 𝑟

    Here n is the refractive index. Remember that n>1


    Another equation for refractive index is

    𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝑣𝑎𝑐𝑢𝑢𝑚 𝑐


    𝑅𝑒𝑓𝑟𝑎𝑐𝑡𝑖𝑣𝑒 𝑖𝑛𝑑𝑒𝑥, 𝑛 = =
    𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝑚𝑒𝑑𝑖𝑢𝑚 𝑣

    Note: The greater the refractive index, the denser is the medium. Hence,
    the speed of light in the medium will be slower.

    Total internal reflection and the critical angle

    Where

    1
    𝑛=
    sin 𝑐
    Note: The light ray must propagate from an optically denser medium to an
    optically less dense medium. The angle of incident must exceed the critical
    angle.

    Some phenomenon related to internal reflection and the critical angle


    1) Mirage
    2) Rainbow

    Converging lens (convex lens)

    There are 3 rules for drawing ray diagram for convex lens

    Note: The characteristics of the image form using a convex lens is always
    either virtual or real; upright or inverted; magnify or diminish. DO NOT
    memorize the characteristics for different object positions. Try to use the 3
    rules and draw them out!!!!

    Dispersion of light

    Refraction by a prism: When light is refracted by a prism, the incidence ray


    is not parallel to the emergent ray, since the prism’s sides are not parallel.
    If a beam of white light is passed through a prism it is dispersed into a
    spectrum. White light is a mixture of colours, and the prism refracts each
    colour by a different amount – red is deviated the least and violet the most.

    Electromagnetic Waves

    Electromagnetic waves are transverse waves. It consists of electric field and


    magnetic field components. It can propagate without the need of a medium
    to carry them unlike mechanical waves. The speed that electromagnetic
    waves travel at is 3x108 ms-1. If this number seems familiar it’s because
    that’s the speed of light. Light is a wave or more specifically an
    electromagnetic wave. There are 7 types of waves in the electromagnetic
    spectrum.

    Mnemonic time!

    R M I V U X G

    3.3 Sound

    Sound waves are mechanical waves as they require a medium to


    propagate through. Another example of mechanical waves is water
    waves and a slinky. Sound waves travel through solid, liquid and gas
    by “passing along” the vibration from one particle to the next. Hence,
    sound travels fastest through , then
    and finally through

    Difference between pitch and loudness:


    Pitch: Is related to the frequency of the sound. The greater the
    frequency, the higher the pitch. Human vocal range is between 80 Hz to
    1100 Hz. Soprano singers would be in the higher range of frequency
    while bass singer would be on the lower! Sound waves less than 20 Hz
    are known as infrasound while those above 20 kHz are known as
    ultrasound.

    Loudness: Is related to the amplitude of the sound. The bigger the


    amplitude the louder the sound.

    Speed of sound is highest in solids (concrete: 5000m/s) then in liquids


    (pure water: 1400m/s) and slowest in gases (air: 330m/s)

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