3.3 Waves Flashcards
What is the function of cladding?
to improve tensile strength of the fibre, prevent scratching, and prevent signal transfer between adjacent fibres
What are diffraction gratings used for
calculating atomic spacing and analysing elements
what is an example of a longitudinal wave
sound waves
how do you prevent material dispersion
using monochromatic light
what is an example of a transverse wave
electromagnetic wave
What is Young’s Double-Slit Experiment
an experiment that demonstrates the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes
How does a light ray move when moving into a medium of lower refractive index?
It speeds up in the lower refractive index material, so it bends away from the normal
What gives evidence for wave nature of light? How?
The double-slit experiment (diffraction and interference); can only be explained by constructive/ destructive interference of waves
What gives evidence for particulate nature of light? Why?
photoelectric effect; beams of light as photons with discrete energy, so can interact with electron one-on-one
Why could photoelectric effect not explain wave theory?
For wave theory, energy is proportional to intensity. The energy would spread evenly and each free electron would get a bit of energy to eventually gain enough energy to leave. But the light actually has to be above a certain frequency to be emitted, meaning it does not emulate wave properties
What is stopping potential?
The p.d. needed to stop the fastest moving electrons with the max kinetic E.
eVs=Ek max
