Waves 0.0 / 5 ? PhysicsWavesGCSEAQA Created by: IJM22Created on: 10-06-19 11:29 What are radio waves used for? To transmit radio and terrestrial TV signals 1 of 24 How does terrestrial TV work? This is received using an aerial e.g. freeview 2 of 24 Why are radio waves used? As they can travel long distances before being absorbed e.g. by buildings and trees 3 of 24 Define diffraction? Spread out 4 of 24 Why are longer wavelength radio waves useful? As they can spread out 5 of 24 How is it possible to send radio waves very long distances around the Earth? As it can reflect off a layer of charged particles in the atmosphere (the ionosphere) 6 of 24 Why are microwaves used for heating waves? Because most foods contain a lot of water molcules and the water molecules can absorb the energy of microwaves 7 of 24 Why else are microwaves used? To communicate with satellites in space because microwaves can pass through the Earth's atompshere without being reflected or refracted 8 of 24 What is infrared emitted by and what is used for? It is emitted by electrical heaters and is also used cook food in ovens 9 of 24 How is infrared used to cook food in ovens? As the energy of infrared is easily absorbed by the surface of objects 10 of 24 Name an important use of visible light? Communication using fibre optics 11 of 24 What are optical fibres? Very thin strands of glass 12 of 24 How do optic fibres work? Pulses of light are transmitted down these fibres and these carry information 13 of 24 Name one use of optical fibres? Telephone and cable TV signals 14 of 24 Why is visible light very good? As it has a short wavelength which means it can carry a great deal of information 15 of 24 Name an important use of ultraviolet? Energy efficient lightbulbs or sun tanning 16 of 24 Why is ultraviolet good for energy efficient lightbulb? As it has a short wavelength which means it carries more energy than visible light 17 of 24 Name a disadvantage of ultraviolet? Increases the risk of skin cancer and causes premature skin ageing 18 of 24 What happens when we bring two magnets close together? They exert a force on each other 19 of 24 What will two like poles do? (South South) They will repel each other 20 of 24 What are the four types of magnetic material Iron, steel, cobalt and nickel 21 of 24 Define a magnetic field? A region around a magnet where a force acts on another magnet or on a magnetic material 22 of 24 How can a direction of a magnetic field be found? By using a compass 23 of 24 What does a magnetic compass contain? A small bar magnet 24 of 24
Comments
No comments have yet been made