Stationary Waves Flashcards
How are gasses identified from emission spectra?
Every gas has specific levels in terms of their diagram.
Each diagram shows different patterns of light.
Every drop of the diagram shows different colour spectrum and each gas has a unique colour of the spectrum.
What are stationary (standing) waves?
When two identical waves travelling in opposite directions, cross each other, they interfere with each other to produce a wave shape that stands still. The product wave is called a stationary wave.
A stationary wave can either result from an interference between two identical waves travelling in opposite direction or a wave interfering with its reflection.
What are nodes?
An area on the wave where the amplitude of the two waves cancel out and a continuous ‘resting point’ is formed on the stationary wave.
What are antinodes?
This is the point on the standing wave where the amplitude of the two waves adds up to create a larger resultant wave.
What happens if you increase the frequency of a wave?
There will be more nodes and antinodes appearing on the standing wave.
This also decreases the wavelength.
Give two examples of applications of stationary waves.
Radio and TV antennas, microwave ovens.
Describe the link with radio and TV antennas and stationary waves.
Radio and TV antennas have a reflector element that bounces the incoming waves back and creates a stationary wave pattern.
The detector is placed at an antinode position for the particular wavelength of radiation the aerial has been designed to pick up.
Describe the link with microwave ovens and stationary waves.
In microwave ovens, stationary waves patterns, caused by reflections from the metal sides of the oven, cause hot and cold spots corresponding to antinodes and nodes.
This is why you need the turntable to rotate the food!
You can use this idea to find the wavelength of a microwave – and go on to prove the speed of light!!!
