Term
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Definition
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A wave is moving energy.
A sound wave is moving sound energy.
A light wave is moving light energy.
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Term
| What is wavelength and how do you measure it? |
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Definition
Wavelength is the length of a single wave. Measure the distance between two consecutive crests
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Term
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Definition
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Frequency is the number of waves that travel passed a point in 1 second. Frequency is measured in Hertz (Hz)
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Term
What is the speed of the following waves in a vacuum a. light b. radiowaves c. microwaves d. x-rays e. ultraviolet |
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Definition
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The answer to all of these questions is 300,000,000 m/s. All waves that belong to the electromagnetic spectrum travel at the same speed in a vacuum.
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Term
| Name the seven waves that make up the electromagnetic spectrum in order from largest to smallest wavelength. |
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Definition
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Radiowaves, Microwaves, Infra red, Visible light, Ultra-violet, X-rays and Gamma rays. This sentence could help you to remember this order. Rude Monkeys Invented Very Unhealthy X-Rated Games
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Term
| Which two waves from the electromagnetic spectrum can we detect? |
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Definition
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Visible light - our eyes are designed to detect this. Infra-red - our skin is designed to detect this. SOund by the way is not a member of the electromagentic spectrum.
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Term
Radiowaves and microwaves are both used for long distance communication. How are they different? How are they used for communications? |
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Definition
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They have different wavelengths. Radiowaves are longer than microwaves. Radiowaves are reflected of the Earth's outer atmosphere and surface till they reach their destination. Microwaves are transmitted (pass through) the atmosphere and use satellites to send signals around the world.
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Term
Which wave can be used to look inside the body? What substance can these waves pass through? What substance absorb them? |
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Definition
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X-rays can be used to look inside the body at our bones. X-rays can pass through flesh but are absorbed by bones. An x-ray shows the x-ray shadow as it passed through your body.
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Term
| What waves can be used for communication using optic fibres? |
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Definition
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Infra-red or visible light can be sent through optic fibres.
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Term
| Which waves can be used for cooking food? |
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Definition
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Infra-red - cooks the food from the outside when atoms absorbs infra-red radiation and get hotter. Then heat travels through the food by conduction. Microwaves - the water molecules in food absorb the microwaves and move more(get hotter).
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Term
| What happens to the electrons in an aerial when it absorbs radiowaves. |
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Definition
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The electrons start to vibrate and create an electric current. The electric current has the same frequency as the radiowaves.
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Term
| What two things can happen to a substance if it absorbs a wave? |
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Definition
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The substance will either warm up or an electric current will be created in the substance.
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Term
| Which three waves when absorbed by living tissue can cause cancer? |
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Definition
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If living tissue absorbs ultra-violet, x-rays or gamma rays then it could damage the cells and cause cancer.
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Term
What is emitted by the Sun which can cause cancer? What substance in the atmosphere absorbs it? What substance can you use to absorb it as well? |
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Definition
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The Sun emits ultra-violet radiation which can cuase skin cancer. The best way to avoid this risk is to stay out of the Sun or wear suncream which absorbs ultraviolet. The ozone layer in the atmosphere also absorbs ultraviolet but we have damaged this and more ultraviolet is reaching the North and South pole regions.
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Term
| Why can ultra-violet be used for security? |
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Definition
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Fluoresence chemicals will not reflect visible light so appear to be invisble normally however they will absorb ultra-violet radiation from special torches and then emit this energy as visible light. This can be used to make invisible security markings on bank notes and
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