Wave Properties (amplitude, wavelength, frequency, period)

    OCR
    GCSE

    Waves are defined as oscillations that transfer energy and information without transferring matter, quantified by specific variables: amplitude, wavelength, frequency, and period. The fundamental wave equation, v = fλ, mathematically links wave speed to frequency and wavelength, while the period is the inverse of frequency (T = 1/f). Candidates must distinguish between transverse and longitudinal wave properties and interpret these variables accurately from both displacement-distance and displacement-time graphs.

    0
    Objectives
    3
    Exam Tips
    3
    Pitfalls
    4
    Key Terms
    4
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Award 1 mark for defining wavelength as the distance between two consecutive corresponding points on a wave (e.g., peak to peak or compression to compression)
    • Award 1 mark for identifying amplitude as the maximum displacement from the equilibrium (rest) position, not the peak-to-trough distance
    • Credit responses that correctly substitute values into v = fλ before calculation
    • Award 1 mark for determining the period (T) from the frequency using the relationship T = 1/f, ensuring time is in seconds

    Example Examiner Feedback

    Real feedback patterns examiners use when marking

    • "You correctly identified the wavelength, but check your definition of amplitude—it is measured from equilibrium, not peak-to-trough"
    • "Good calculation of wave speed. Ensure you show the conversion from cm to m explicitly to guarantee full credit"
    • "You have confused period and frequency here. Remember that Period = 1 / Frequency"
    • "Excellent use of the wave equation. To reach the top band, practice rearranging the formula to find frequency when speed and wavelength are known"

    Marking Points

    Key points examiners look for in your answers

    • Award 1 mark for defining wavelength as the distance between two consecutive corresponding points on a wave (e.g., peak to peak or compression to compression)
    • Award 1 mark for identifying amplitude as the maximum displacement from the equilibrium (rest) position, not the peak-to-trough distance
    • Credit responses that correctly substitute values into v = fλ before calculation
    • Award 1 mark for determining the period (T) from the frequency using the relationship T = 1/f, ensuring time is in seconds

    Examiner Tips

    Expert advice for maximising your marks

    • 💡When analyzing wave graphs, check the x-axis label immediately: a displacement-distance graph gives wavelength, whereas a displacement-time graph gives period
    • 💡Always write down the equation v = fλ before substituting values; OCR often awards a compensation mark for the equation even if the arithmetic follows incorrectly
    • 💡Pay close attention to prefixes in unit labels; 'kHz' requires multiplication by 1000, and 'ms' (milliseconds) requires division by 1000 to convert to standard units

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Identifying amplitude as the total vertical distance from peak to trough rather than from the equilibrium line to the peak
    • Failing to convert wavelengths given in centimetres (cm) or millimetres (mm) into metres (m) before calculating wave speed
    • Confusing the definitions of period and frequency, often stating period is the number of waves per second rather than the time for one complete wave

    Study Guide Available

    Comprehensive revision notes & examples

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    Key Terminology

    Essential terms to know

    Definitions of amplitude, wavelength, frequency, and period
    Application of the wave equation (v = fλ)
    Graphical representation (displacement-distance vs displacement-time)
    Relationship between period and frequency (T = 1/f)

    Likely Command Words

    How questions on this topic are typically asked

    Define
    Calculate
    Describe
    Explain
    Determine

    Practical Links

    Related required practicals

    • •{"code":"PAG P5","title":"Investigation of the properties of waves","relevance":"Using a ripple tank to measure frequency and wavelength to calculate wave speed"}

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