Wednesday, 27 August 2025

Week 7 Term 3 2024 - Basic Wave Properties, Standing Waves & Music, The Doppler Effect

 Homework

Basic Wave Properties

  • Act 4A, p.56 Properties of Waves

Standing Waves & Music
  • Act 5A, p.73-74 Standing Waves
  • Act 5B, p.79-80 Music

  • Ex 3D, p.75-79, Standing Waves and Music


The Doppler Effect
  • Act 6A, p.85-86 The Doppler Effect


    • Longitudinal Waves

    Particle displacement in the medium is parallel to the direction of wave propagation e.g. sound waves, primary earthquake waves

    Transverse Waves
    Particle displacement in the medium is perpendicular to the direction of wave propagation e.g. light and other electromagnetic waves, secondary earthquake waves

    Frequency - Period


    Sound Waves
    Superposition of Waves

    Waves travel through each other and the total amplitude at any moment is equal to the sum of amplitudes of the individual waves.


    Standing Waves
    In musical instruments - when a reflected wave travels back through itself causing fixed points of Nodes (Deconstructive Interference) and Antinodes (Constructive Interference) due to the fractional relationship between the wavelength (𝜆) of the wave and the length (L) of the resonating chamber

    in musical instruments - when a reflected wave travels back through itself causing fixed points of Nodes (Deconstructive Interference) and Antinodes (Constructive Interference) due to the fractional relationship between the wavelength (𝜆) of the wave and the length (L) of the resonating chamber


    Harmonic
    String
    Double Open Ended Pipe
    Closed Ended Pipe
    1st
    𝜆 = 2L
    f = f1st
    𝜆 = 2L
    f = f1st
    𝜆 = 4L
    f = f1st
    2nd
    𝜆 = L
    f = 2f1st
    𝜆 = L
    f = 2f1st

    3rd
    𝜆 = ⅔ L
    f = 3f1st
    𝜆 = ⅔ L
    f = 3f1st
    𝜆 = 4/3 L
    f = 3f1st
    4th
    𝜆 = ½ L
    f = 4f1st
    𝜆 = ½ L
    f = 4f1st

    5th
    𝜆 = ⅖ L
    f = 5f1st
    𝜆 = ⅖ L
    f = 5f1st
    𝜆 = ⅘ L
    f = 5f1st

    Standing Waves Part I: Demonstration


    Standing Waves Part II: Explanation

    Standing Waves


    Standing Waves on a String
    1st Harmonic
    2nd Harmonic
    3rd Harmonic
    4th Harmonic
    𝜆 = 2L
    𝜆 = L
    𝜆 = ⅔ L
    𝜆 = ½ L
    f = f1st
    f = 2f1st
    f = 3f1st
    f = 4f1st


    Standing Waves in a Pipe


    Standing Waves in a Wave Tank


    Standing Waves on a 2D Plate

    Cymatics

       Acoustic Levitation in ULTRA SLOW MOTION


    Timbre
    Timbre is caused by the shape of the repeating wave unit. This gives instruments their characteristic sound even when playing the same note

     Musical Notes and Frequencies
("Middle C" is C4 )

NoteFrequency (Hz)Wavelength (cm)
C016.352109.89
 C#0/Db0 17.321991.47
D018.351879.69
 D#0/Eb0 19.451774.20
E020.601674.62
F021.831580.63
 F#0/Gb0 23.121491.91
G024.501408.18
 G#0/Ab0 25.961329.14
A027.501254.55
 A#0/Bb0 29.141184.13
B030.871117.67
C132.701054.94
 C#1/Db1 34.65995.73
D136.71939.85
 D#1/Eb1 38.89887.10
E141.20837.31
F143.65790.31
 F#1/Gb1 46.25745.96
G149.00704.09
 G#1/Ab1 51.91664.57
A155.00627.27
 A#1/Bb1 58.27592.07
B161.74558.84
C265.41527.47
 C#2/Db2 69.30497.87
D273.42469.92
 D#2/Eb2 77.78443.55
E282.41418.65
F287.31395.16
 F#2/Gb2 92.50372.98
G298.00352.04
 G#2/Ab2 103.83332.29
A2110.00313.64
 A#2/Bb2 116.54296.03
B2123.47279.42
C3130.81263.74
 C#3/Db3 138.59248.93
D3146.83234.96
 D#3/Eb3 155.56221.77
E3164.81209.33
F3174.61197.58
 F#3/Gb3 185.00186.49
G3196.00176.02
 G#3/Ab3 207.65166.14
A3220.00156.82
 A#3/Bb3 233.08148.02
B3246.94139.71
C4261.63131.87
 C#4/Db4 277.18124.47
D4293.66117.48
 D#4/Eb4 311.13110.89
E4329.63104.66
F4349.2398.79
 F#4/Gb4 369.9993.24
G4392.0088.01
 G#4/Ab4 415.3083.07
A4440.0078.41
 A#4/Bb4 466.1674.01
B4493.8869.85
C5523.2565.93
 C#5/Db5 554.3762.23
D5587.3358.74
 D#5/Eb5 622.2555.44
E5659.2552.33
F5698.4649.39
 F#5/Gb5 739.9946.62
G5783.9944.01
 G#5/Ab5 830.6141.54
A5880.0039.20
 A#5/Bb5 932.3337.00
B5987.7734.93
C61046.5032.97
 C#6/Db6 1108.7331.12
D61174.6629.37
 D#6/Eb6 1244.5127.72
E61318.5126.17
F61396.9124.70
 F#6/Gb6 1479.9823.31
G61567.9822.00
 G#6/Ab6 1661.2220.77
A61760.0019.60
 A#6/Bb6 1864.6618.50
B61975.5317.46
C72093.0016.48
 C#7/Db7 2217.4615.56
D72349.3214.69
 D#7/Eb7 2489.0213.86
E72637.0213.08
F72793.8312.35
 F#7/Gb7 2959.9611.66
G73135.9611.00
 G#7/Ab7 3322.4410.38
A73520.009.80
 A#7/Bb7 3729.319.25
B73951.078.73
C84186.018.24
 C#8/Db8 4434.927.78
D84698.637.34
 D#8/Eb8 4978.036.93
E85274.046.54
F85587.656.17
 F#8/Gb8 5919.915.83
G86271.935.50
 G#8/Ab8 6644.885.19
A87040.004.90
 A#8/Bb8 7458.624.63
B87902.134.37
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Thursday, 7 August 2025

Week 4 Term 3 2025 Inductors

  Basic Circuit Revision

  • Act 13A, p.205-206 Level 2 D.C. Circuit Revision


Internal Resistance of a Battery

  • Act 13B, p.210-211 Internal Resistance of a Battery

  • Ex 6B, P.261-262 Internal Resistance of a Battery


Resistor Networks (Resistors in Series and Parallel)

  • Ex 6A, p.251-253 Resistor Networks


Kirchhoff’s Laws

  • Act 13C, p.214-216 Kirchhoff's Laws

  • Ex 6C, p.267-272 Kirchhoff's Laws


Capacitors

  • Act 14A, p.240 Capacitance & Capacitors

  • Act 14B, p.244-245 Capacitor Networks & Energy

  • Act 14C, p.249-251 Charging & Discharging Capacitors

  • Ex 6D, p.277-280 Capacitor Energy

  • Ex 6E, p.283-284 Capacitors

  • Ex 6F, p.289-292 Capacitor Networks

  • Ex 6G, p.298-300 Charging & Discharging Capacitors


Inductors

  • Act 15A, p.259-260 Induced Voltage & Current

  • Act 15B, p.263-264 Transformers

  • Act 15C, p.268-269 Inductance

  • Act 15D, p.272-273 Voltage and Current Graphs for the Inductor

  • Ex 6H, p.303-305 Inductance in DC Circuits

  • Ex 6I, 308-310 Inductance: Self; Mutual; Time Constant; Energy Stored

  • Ex 6J, p.311-312 Transformers


Right Hand Screw Rule


Right Hand Slap Rule

Magnetic Flux










Lenz's Law

Faraday's Law & Lenz's Law


Inductance


Inductors Explained - The basics how inductors work working principle








Transformers


The ratio of the secondary to primary voltage is equal to the ratio of the secondary to primary turns

Vs/Vp = Ns/Np

In an Ideal Transformer 
Secondary Power = Primary Power
In reality, energy is lost through heat from eddy currents generated in the soft iron core from the changing flux.

NB: As Voltage is often referred to as e.m.f. the Symbol "e" or "E" is often used in engineering to refer to e.m.f.
This is the case in the video below.
After explaining how basic Transformers work, this video goes on to explain 3-Phase Transformers.

NZ Street Step-Down Transformer

Internal Diagram of a Transformer

How Do Substations Work?

Fuse MCB, How it Works
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