441081
Description
Mind Map by olivia.jermy, updated more than 1 year ago
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Created by olivia.jermy
over 10 years ago
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P1 Revision (continued)
- A spectrum of waves
- Transverse waves- travels in a direction at
right angles to the water vibration
- Amplitude- the maximum displacement of a particle from its
rest position
- Wavelength(m)- distance between two successive points
on the wave
- Frequency(Hz)- number of complete waves passing a point in one
second
- Crest- point of maximum
displacement above the rest position
- Trough- maximum displacement below the
rest position
- wave speed(m/s)= frequency x wavelength
- Transverse waves- travels in a direction at
right angles to the water vibration
- Electromagnetic spectrum
- Radio waves- lowest frequency
- All electromagnetic waves travel in
straight lines through a particular medium
- They can be reflected and refracted
- (REFLECTION) When a ray of light hits a mirror the angle of
incidence is equal to the angle of reflection
- (REFRACTION)When light passes from one medium into another at an
angle to the boundary, it changes direction. This
sometimes produces off effects at the boundary
between two mediums
- Some are used for communication
- When a wave travels from one medium into another, the frequency of the
incident wave does not change. The wavelength does because the speed of
the wave changes. Electromagnetic waves slow down in a denser medium
- When they are incident at an angle to the boundary, this change in
speed causes the wave direction to change. This is known as
refraction
- In communications the size of the receiver depends on the wavelength of
the wave. The longer the wavelength, the longer the receiver needs to be
- When waves pass through an opening they spread out. This is known as diffraction
- Radio waves- lowest frequency
- Light and lasers
- Light
Amplification by
Stimulated
Emission of
Radiation
- A laser produces a narrow intense beam of light of a
single colour (monochromatic)
- Uses of lasers- Communication, dental treatment, weapon
guidance, surgery, light shows and bar code readers
- Morse code- series of dots and dashes that represent individual letters in the
alphabet. This is a digital signal. To cover large distances, the signals are relayed
from one signal station to another
- Signals can be sent by light, electricity, radio waves or microwaves
- White light- made up of many different colours, each of a
different frequency and out of phase
- Light from a laser is at one frequency and in phase
- Monochromatic- single colour from one frequency
Coherent- in phase
- A beam is a monochromatic coherent beam. The beam does not
diverge very much
- CD- series of fine pits. Pits represent a digital signal, the
signal is read by a laser
- The music layer is coated with a fine film of metal that follows the pits exactly.
The shiny metal film reflects the laser light. The metal layer is covered by another
layer of transparent plastic. The music is sandwiched between two layers of
plastic. This stops dust and scratches from affecting the sound
- The music layer is coated with a fine film of metal that follows the pits exactly.
The shiny metal film reflects the laser light. The metal layer is covered by another
layer of transparent plastic. The music is sandwiched between two layers of
plastic. This stops dust and scratches from affecting the sound
- Light can stay inside glass, Perspex and water. Denser than air, light reflected at the
boundary between material and air (total internal reflection)
- Optical fibres
- Light, infra red radiation and laser beams can travel along a piece of solid glass. Every time the light meets
the boundary with air, it is reflected back into the fibre
- They're very flexible and the signals are coded and sent using laser light or infra red
- Transmit data at 200,000 km/s (speed of light in glass)
- Work because the angle of incidence is greater than the critical angle
and they have a coating around them to improve reflection
- Light, infra red radiation and laser beams can travel along a piece of solid glass. Every time the light meets
the boundary with air, it is reflected back into the fibre
- Critical angle
- When light is passing through a more dense material to a less dense material the angle of
refraction is greater than the angle of incidence. If the angle of incidence increases, it is
possible that the angle of refraction could be a right angle. When this happens the angle of
incidence is called the critical angle
- Total internal reflection
- If the angle of incidence is increased even more, the light is reflected back inside the more dense material
- If the angle of incidence is increased even more, the light is reflected back inside the more dense material
- Total internal reflection
- When light is passing through a more dense material to a less dense material the angle of
refraction is greater than the angle of incidence. If the angle of incidence increases, it is
possible that the angle of refraction could be a right angle. When this happens the angle of
incidence is called the critical angle
- Endoscopy
- Light passes along the outer fibres and lights up patient. The
reflected light passes back along the inner fibres and the image
is viewed through an eyepiece
- Light passes along the outer fibres and lights up patient. The
reflected light passes back along the inner fibres and the image
is viewed through an eyepiece
- Light
Amplification by
Stimulated
Emission of
Radiation
Media attachments
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