Electromagnetic waves and wave experiments Flashcards
Give 3 examples of electromagnetic waves?
light, x-rays and microwaves
How are they unlike other waves?
They don’t need a medium like air or water to travel through.
Instead they travel through a vacuum like space, which is how light and infrared waves reach the Earth from the Sun.
What is the electromagnetic spectrum?
The family formed from different types of electromagnetic waves.
This ranges from long wavelengths to very, very short ones.
Name all the waves in the electromagnetic spectrum in order from least energy to most/largest wavelength to smallest/lowest frequency to largest?
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays.
Do all electromagnetic waves travel in straight lines?
yes
What speed do the different waves travel at?
Despite having different wavelengths, frequencies and energies, they all travel through space at the same speed. This is the speed of light, or 300,000,000 m/s
What can we draw to show reflection?
Simple ray diagrams
What is the normal line in a ray diagram?
A line of 90* to the surface, we always measure angles to the normal.
What does the law of reflection state?
The angle of incidence is always equal to the angle of reflection, even if the surface is really rough, the two angles are always the same.
Can all waves be reflected and refracted?
yes
What is refraction?
All waves can be refracted.
Refraction can lead to strange effects such as a pencil looking bent in water.
When waves go to one medium to another they can be refracted.
As they enter their speed changes and this causes a change in direction.
If the wave slows down it bends towards the normal, but if it speeds up it bends away from the normal.
What is diffraction?
Whenever the waves pass through a gap or move around an obstacle, they spread out.
The size of the gap relative to the wavelength of the wave affects how much diffraction takes place.
In general, the longer the wavelength or the smaller the gap, the greater the diffraction.
The strongest diffraction occurs when the gap is the same size as the wavelength.
How does diffraction cause problems when using optical instruments?
When light enters the instrument, it passes through a small gap and diffracts a little. This can lead to a blurry image or a loss of detail in a microscope, telescope, etc.
