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Radio waves & visible light have very little effect on cells. Microwaves and infrared can cause heating of cells. X-rays, UV and gamma rays can.
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What do waves transfer? (They do this without transferring what?) What do all electromagnetic waves have in common? What is a longitudinal wave and what does it look like? Draw and label this wave: - What can happen when radiation is absorbed by a substance? Name the electromagnetic spectrum from shortest to longest wavelength Question Question Question Question Question Question
Frequency โ number of waves produced each second (Hz) Gamma (shortest) X-rays Ultra-violet Visible light Infra red Microwaves Radio waves (longest) Radiation may make things hotter, or set up an alternating current with the same frequency as the radiation itself Transfer energy without transferring matter Vibrations in the same direction as the wave (e.g. sound) They all travel at the same speed through a vacuum โ the speed of light (300โ000โ000m/s) Answer Answer Answer (^) Answer Answer Answer
Reducing exposure & using lead aprons Radio waves: communications Microwaves: heating food & sending information (e.g. mobile phones) UV: security tags and sun-beds X-rays: imaging the body (broken bones) Radio waves & visible light have very little effect on cells Microwaves and infrared can cause heating of cells X-rays, UV and gamma rays can cause ionization of cells and lead to mutations, cancers and death Infrared: communications (phone & via optical fibres), remote controls and electric heaters Visible light: used to send information via optical fibres Reduce exposure to the Sun (using a broad spectrum sun screen) Answer (^) Answer Answer (^) Answer Answer Answer
How are gamma rays used? Why are microwaves used to communicate with satellites? What are rarefactions and compressions? Which 4 forms of electromagnetic radiation can be used for communications? What is the formula for calculating the speed of a wave (triangle will also help) What is a transverse wave and what does it look like? Question Question Question Question Question Question
What properties effect waves? What is refraction? How can the refractive index be worked out? How can light be reflected? What is constructive interference? Draw out an angle of incidence and an angle of reflection Question Question Question Question Question Question
Light can reflect off an even surface (clear) or from an uneven surface (diffuse) Angle of incidence = angle of reflection Where two waves arrive in step reinforcing one another (increasing the amplitude) Waves can be reflected, refracted and diffracted Refractive index = sin i รท sin r Refraction occurs as light can bend at the boundary between materials of different densities Answer Answer Answer (^) Answer Answer Answer
Where two waves arrive out of step cancelling one another out Reflection Refraction Diffraction increases Refraction Diffraction increases Answer (^) Answer Answer (^) Answer Answer Answer
What does this picture show? How do optic fibres work, and what are they used for? What does the red- shift provide evidence for? How do people who work with radiation monitor their exposure? Question Question Question Question What is red-shift? What is cosmic microwave background radiation? Question Question
What is amplitude? What properties does an image in a plane mirror have? What is pitch? Draw an image as shown in a plane mirror What type of EM radiation can we detect? What colour of light is refracted the most and why? Question Question Question Question Question Question
Pitch is how high or low a sound is, dependent upon the frequency of the waves Plane mirror image A measure of how loud a sound is (how much energy is carried) Image is the same size, it is as far behind the mirror as the object is in front, and it is formed from diverging rays meaning it is virtual Answer (^) Answer Answer (^) Answer Violet (it has the shortest wavelength) Visible light Answer (^) Answer
