Waves Part 2 Flashcards
Explain the difference between speculator and diffuse light in reflection…
Specular reflection is light reflected from a smooth shiny surface eg- mirror, whereas diffuse reflection is reflected from rough surfaces that tend to reflect light in all directions e.g.- clothing and paper
Why does a yellow hat look yellow?
As the white light hits the yellow surface the light reflected is yellow, this is because red and green (that make yellow) are reflected and blue is absorbed.
Why does a white object look white?
It looks white because it reflects all of the colours
What colour is a mixture of red and blue?
Magenta
Why does a blue book look blue?
All the other colours are absorbed apart from blue as It is reflected
What would happen if I shon a white torch through a red filter?
Red light would come out the other side, this is because the red filter only allows red through, all the other colours on the spectrum are absorbed
What would happen if white light was shon through a red and green filter that were placed together?
The light would appear black because the red filter would only allow red light through and the green would only allow pure green though, this means the light passing through is blocked wouldn’t allow light through, therefore it would appear black
Which is more powerful; a lens with a shorter focal length or a lens with a longer focal length?
A shorter focal length
What are the properties of a converging lens?
The lines cross
Convex shape
If the object is far away the image looks upside down but if it’s close up it is magnified and upright
What are the properties of a diverging lens?
Lines get further apart Concave shape Virtual image Upright Everything's small
What is a real Image
It’s an image formed where the light rays are focused
What is a virtual image
Is an image from which the light rays appear to come but don’t actually come from the image e.g. Mirror
What are electromagnetic waves?
Transverse waves that travel at the same speed in a vacuum, they transfer energy from source to observer
Recall the main groupings of the continuous electromagnetic spectrum - in order
Radio waves Microwaves Infrared Visible spectrum Ultraviolet X rays Gamma rays
Describe the electromagnetic spectrum as…….
Continuous from radio waves to gamma rays and that the radiations within it can be grouped in order of decreasing wave length and increasing frequency
How does a body stay at a constant temperature
It needs to radiate the same average amount of power it absorbs
What does the intensity and wave length distribution of any emission depend on?
Temperature
What happens to a body if the average power it radiates is less or more than the power it absorbs
It will over or under heat eg- global warming
Bad effects of microwaves
Internal heating of body cells
Bad effects of infrared
Burning skin
Bad effects of ultraviolet
Damage to surface of cells and eyes, leading to skin cancer and eye conditions
Bad effects of X-rays and gamma rays
Mutation or damage to cells in the body
Uses of radio waves
Broadcasting, communications and satellite transmission
Uses of microwaves
Cooking, communications and satellite transmissions
Uses of infrared
Cooking, thermal imaging, short range communication, optical fibres, television remote controls and security systems
Uses of visible light
Vision
Photography
Illumination
Uses of ultra violet
Security marking, fluorescent lamps, detecting forged bank notes and disinfecting water
Uses of X-rays
Observing interns structures of objects, air port security cameras and medical X-rays
Uses of gamma rays
Sterilising food, medical equipment and the detection of cancer and its treatment
Changes in atoms and nuclei can…
Generate radiations over a wide frequency range
Be caused by absorption of a range of radiations
Radio waves can be…
Produced by, or can themselves induce, oscillations in electrical circuits
