93717
Descrição
Mapa Mental por jamiemcparlin, atualizado more than 1 year ago
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Criado por jamiemcparlin
mais de 11 anos atrás
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P7: Waves, lenses and telescopes
- Light and sound travel in waves.
These waves can be:
- Refracted
- This is caused when waves cross a
boundary between one medium and another
- The frequency is the same but there is a
change in wavelength
- This leads to a change in wave speed
- Which causes a change in wave
direction
- Which causes a change in wave
direction
- This leads to a change in wave speed
- The frequency is the same but there is a
change in wavelength
- The colours that make up white light are
refracted by different amounts as they
pass through a prism
- Red light is refracted the most
- Violet light is refracted the least
- This occurs because the colours that make up white
light have different frequencies and wavelengths
- Red light is refracted the most
- This is caused when waves cross a
boundary between one medium and another
- Defracted
- This is caused when waves move
through a narrow gap or past an
obstacle
- Diffraction is most obvious when:
- The size of the gap is smaller or
the same size as the wavelength
of the wave
- The waves that pass obstacles
have long wavelengths
- The size of the gap is smaller or
the same size as the wavelength
of the wave
- Radiation is diffracted by
the aperture of a telescope
- to produce sharp images, the aperture
must be a lot bigger than the wavelength of
the radiation detected by the telescope
- to produce sharp images, the aperture
must be a lot bigger than the wavelength of
the radiation detected by the telescope
- Diffraction is most obvious when:
- This is caused when waves move
through a narrow gap or past an
obstacle
- Refracted
- Convex/converging Lenses
- These bend rays of light inwards as
it passes through the lens
- If the rays of light are parallel, the rays of
light will be brought to focus at the focal point
- This is due to refraction
- This is due to refraction
- The greater the curvature of the
lens, the more powerful it will be
- This means that of two lenses made of the same
material, the one with the biggest curvature will be
more powerful
- You can calculate the power of the lens using a formula
- Power (dioptres) = 1/ focal length
- The focal length is the distance
between the focal point and the lens
- The focal length is the distance
between the focal point and the lens
- Power (dioptres) = 1/ focal length
- This means that of two lenses made of the same
material, the one with the biggest curvature will be
more powerful
- If the rays of light are parallel, the rays of
light will be brought to focus at the focal point
- These bend rays of light inwards as
it passes through the lens
- Telescopes
- A simple refracting telescope is made from two
converging lenses of different powers
- The eye piece lens is more powerful
than the objective lens
- The objective lens captures parallel light from a
different object and brings it to a point on the focal point
of the lens
- This point is also the focal point for the eyepiece lens. So the image acts as
an object and the eyepiece lens magnifies it
- the distance between the lenses will be equal to the
focal lengths of the objective and eyepiece lenses
added together
- the distance between the lenses will be equal to the
focal lengths of the objective and eyepiece lenses
added together
- This point is also the focal point for the eyepiece lens. So the image acts as
an object and the eyepiece lens magnifies it
- The objective lens captures parallel light from a
different object and brings it to a point on the focal point
of the lens
- The eye piece lens is more powerful
than the objective lens
- One type of telescope is an
astronomical (reflecting) telescope
- This uses a concave mirror instead of a
convex mirror for the objective lens
- This allows the telescope to be larger
so it takes in more light
- The larger the telescope, the more detail
the image it produces has
- The larger the telescope, the more detail
the image it produces has
- Concave mirrors reflect rays of
parallel light and bring them to focus
- This allows the telescope to be larger
so it takes in more light
- This uses a concave mirror instead of a
convex mirror for the objective lens
- A simple refracting telescope is made from two
converging lenses of different powers
- Angular magnification
- The image of a disant magnified object will appear
closer than the actual object is
- So the angles made by ray lines entering the eye is greater
- the increase in angle is called angular magnification
and makes the object appear closer
- the increase in angle is called angular magnification
and makes the object appear closer
- So the angles made by ray lines entering the eye is greater
- You can calculate the angular magnification
of a telescope using a formula
- Magnification= Focal length of objective lens / focal length of eyepiece lens
- Magnification= Focal length of objective lens / focal length of eyepiece lens
- The image of a disant magnified object will appear
closer than the actual object is
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