TYPES OF WAVES
Mechanical Waves – They need matter (or medium) to transfer energy.
- Sound does not travel in vacuum
- A rope vibrating forms a wave
- Water waves
Electromagnetic Waves – They do not need a medium, but some can go through matter.
They can travel even through empty space.
- Light travels through empty space
- X-rays can pass through matter revealing bones in our body
Characteristics of Transverse Waves
- Crest or peak: the highest part of the disturbance on a wave
- Trough: the lowest part of the disturbance on a wave
- Amplitude: the “height” of the wave from the rest point (middle line).
- Wavelength: The distance from one point on a wave to the same point on the next wave (or the distance between two peaks or two throughs. The most common unit of wavelength is the nanometer.
1 meter = 109 nanometer <=====> 1 m = 109 nm
Spectrum of the visible light.
- What is a rainbow? A rainbow is made of the visible part of the electromagnetic spectrum which has been separated into the original colors through rain droplets in the atmosphere.
- We can produce the same effect using a prism to separate the white light into their components.
Line spectra of the elements: Why do we see only certain lines?
Two ways to see the line spectra
- Line spectra of the elements can be seen in two ways
Emission spectra: the element is heated and the emitted light is analyzed.
Absorption Spectra: White Light passing through the gaseous element will absorb the same colors that are observed in the emission light.
Have a look at the video below:
Dual nature of electrons
So Electrons can behave as particles and also as WAVES…
Here you have some details about WAVES we need to know:
Waves Notes: PowerPoint Presentation (PPT format)
waves of visible light can be represented as follows:
Waves Exercises: Worksheet and exercises (PDF format)
LAB : FLAME TEST (PDF) (DUE ONE DAY AFTER THE LAB)
Links to see the line spectra of the elements: