IB Physics HL C 3 8 Two Source Interference Questions
Practise IB Physics HL C.3.8 by solving two-source fringe, intensity and geometry problems for light, sound and water waves.
- Syllabus
- First assessment 2025
- Course
- Physics HL
- Level
- HL
Exam points
- Solve fringe spacing, path-difference and intensity changes when wavelength or source separation varies.
- Use phase and path differences to calculate positions of maxima and minima for two coherent sources.
- Analyse multi-source interference patterns and justify changes caused by wavelength or geometry.
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IB Physics HL C 3 8 Two Source Interference Questions question 1
A student investigates how light can be used to measure the speed of a toy train.
Light from a laser is incident on a double slit. The light from the slits is detected by a light sensor attached to the train.
The graph shows the variation with time of the output voltage from the light sensor as the train moves parallel to the slits. The output voltage is proportional to the intensity of light incident on the sensor.
Explain, with reference to the light passing through the slits, why a series of voltage peaks occurs.
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