Waves

    OCR
    GCSE

    Waves facilitate the transfer of energy and information without the net transfer of matter, distinguishing between transverse oscillations perpendicular to propagation and longitudinal oscillations parallel to propagation. Analysis requires the application of the wave equation to calculate speed, frequency, and wavelength across both mechanical and electromagnetic systems. Understanding boundary behaviors, specifically reflection and refraction, is essential for explaining phenomena such as optical illusions and the practical applications of the electromagnetic spectrum.

    0
    Objectives
    3
    Exam Tips
    4
    Pitfalls
    4
    Key Terms
    5
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Award 1 mark for explicitly stating that oscillations in transverse waves are perpendicular to the direction of energy transfer
    • Credit correct substitution of values into the equation wave speed = frequency × wavelength before rearrangement
    • Award 1 mark for identifying that frequency remains constant while speed and wavelength change during refraction
    • Credit diagrams that show the normal drawn at 90 degrees to the boundary at the point of incidence
    • Award marks for describing the use of a strobe light or camera to freeze waves for measurement in ripple tank contexts

    Example Examiner Feedback

    Real feedback patterns examiners use when marking

    • "You correctly calculated the speed, but missed the unit conversion for wavelength — always check for 'cm' vs 'm'"
    • "Good definition of transverse waves, but ensure you specify 'energy transfer' direction, not just 'wave direction'"
    • "You identified that the wave slows down, now explain how this causes the change in direction (refraction)"
    • "Excellent use of the wave equation; to secure top marks, show your rearrangement step clearly before calculating"

    Marking Points

    Key points examiners look for in your answers

    • Award 1 mark for explicitly stating that oscillations in transverse waves are perpendicular to the direction of energy transfer
    • Credit correct substitution of values into the equation wave speed = frequency × wavelength before rearrangement
    • Award 1 mark for identifying that frequency remains constant while speed and wavelength change during refraction
    • Credit diagrams that show the normal drawn at 90 degrees to the boundary at the point of incidence
    • Award marks for describing the use of a strobe light or camera to freeze waves for measurement in ripple tank contexts

    Examiner Tips

    Expert advice for maximising your marks

    • 💡When describing the ripple tank experiment, specify measuring '10 waves' and dividing by 10 to reduce uncertainty
    • 💡Memorize the standard form prefixes: k (10^3), M (10^6), and G (10^9) as these are frequently used in frequency questions
    • 💡In refraction questions, explicitly link the change in direction to the change in speed; 'bending' alone is often insufficient for higher marks

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Confusing the direction of 'wave motion' with the direction of 'oscillation' when defining wave types
    • Failing to convert wavelength from centimeters (cm) or millimeters (mm) into meters (m) prior to calculation
    • Incorrectly stating that water molecules move across the tank rather than oscillating about a fixed position
    • Drawing wavefronts that change frequency (spacing) without a corresponding change in speed during refraction

    Key Terminology

    Essential terms to know

    Transverse and longitudinal wave mechanics
    The wave equation and period calculation
    Electromagnetic spectrum properties and trends
    Reflection and refraction at boundaries

    Likely Command Words

    How questions on this topic are typically asked

    Calculate
    Describe
    Explain
    Draw
    Suggest

    Practical Links

    Related required practicals

    • •{"code":"PAG P5","title":"Measuring Wave Properties","relevance":"Measurement of wave speed in liquids (ripple tank) and solids"}

    Ready to test yourself?

    Practice questions tailored to this topic