Physics OCR A Level. Waves: Module 4: Electrons, Waves and Photons: Questions with Complete Solutions

1. Define the term ‘progressive wave’. A wave that transfers energy from one place to another with a wave front which travels through the material (in contrast to stationary waves which don’t appear to move). 2. What is a longitudinal wave? Waves which the particles oscillate in the same direction as energy propagation. 3. There are rarefactions (areas of low pressure) and compressions (areas of high pressure). 4. What is a transverse wave? Give examples. Waves where the particle oscillations are perpendicular to the energy propagation. For example: electromagnetic waves. 5. Define frequency and give its units. The number of waves passing through a point per second. Units of Hertz (Hz) or s⁻¹. 6. Define wavelength. The distance between two adjacent corresponding points (eg. peaks) on a wave. 7. Define amplitude. The maximum displacement of the wave from its equilibrium position. 8. How can you find out the time period of a wave using it frequency? T = 1/f 9. What is the phase difference of a wave and what is it measured in? The amount one wave lags behind another as a proportion of the wavelength. Measured in radians or degrees. 10. What do each of the ‘axes’ on an oscilloscope measure? Vertical divisions = voltage/amplitude of the wave. Horizontal divisions = time (can be used to find time period and frequency). 11. Define refraction. Refraction is when a wave bends at a boundary between two materials due to the difference in density causing it to speed up or slow down. 12. True or False: A wave can either be refracted or reflected at a boundary, but never both. False. 13. At low angle of incidence most will be refracted, but some will reflect. 14. True or False: Diffraction is most noticeable when the wavelength is much larger than the gap the wave is travelling through. False. The most diffraction is seen when the gap and the wavelength are the same size. If the wavelength is much bigger the waves will be mostly reflected