9478 / 2027

Chapter 11

Superposition

Add the oscillating quantities first, then identify what stays fixed, what is measured and which conditions make a pattern observable.

Explain wave patterns and extract reliable wavelengths, fringe spacings, diffraction angles and resolution limits from them.

Signed superposition, standing waves in strings, microwaves and air columns, coherent two-source interference, double slits, gratings, single-slit diffraction and aperture resolution. For 9478 (2027).

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  1. Add overlapping waves

    Add signed disturbances at a common position and instant, then distinguish the resultant from its component waves.

  2. Build a standing wave

    Combine oppositely travelling waves and distinguish permanent nodes from an instantaneous zero displacement.

  3. Measure string and microwave patterns

    Use the apparatus, controls and several node or minimum intervals to determine wavelength.

  4. Standing sound and air columns

    Distinguish pressure and displacement nodes and use successive resonant air lengths to determine sound wavelength.

  5. Coherence, phase and two sources

    Explain interference in four media and combine source phase with path difference under observable-pattern conditions.

  6. Measure double-slit fringes

    Identify slit separation, screen distance and fringe intervals, then calculate wavelength or a screen position.

  7. Diffraction gratings and wavelength

    Convert line density to spacing, identify allowed principal maxima and measure wavelength from their directions.

  8. Diffraction and a single slit

    Explain spreading at openings and edges, then locate the first minima and the full central-maximum width.

  9. Resolve two sources

    Apply the Rayleigh criterion while distinguishing source separation from diffraction-pattern width.