Flashcards
P2: Physics Flash Cards
Cards in this deck (26)
- 1P2: Physics A photon of which type of electromagnetic radiation will transfer the most energy? Explain why.The higher the frequency of electromagnetic radiation, the more energy is transferred by each photon. Gamma rays have the highest frequency, so each gamma ray photon will transfer more energy than a photon of any other type of electromagnetic radiation.
- 2P2: Physics What is a photon? How does the frequency of electromagnetic radiation affect its photons?Electromagnetic radiation transfers energy in 'packets' called photons. The higher the frequency of electromagnetic radiation, the more energy is transferred by each photon.
- 3P2: Physics List the types of electromagnetic radiation in order of increasing frequency, starting with radio waves.Radio waves, microwaves, infrared radiation, visible light, ultraviolet, x-rays, gamma rays.
- 4P2: Physics What is a source of electromagnetic radiation? What can happen to electromagnetic radiation when it meets a material?A source is anything that emits radiation. Electromagnetic radiation can be absorbed, transmitted or reflected by any material it meets.
- 5P2: Physics What does the amount of energy transferred by a beam of electromagnetic radiation to an object it meets depend on?The number of photons absorbed by the object and energy of each photon.
- 6P2: Physics At what speed does electromagnetic radiation travel through space?All electromagnetic radiation travels at 300,000 km/s through space (a vacuum)
- 7P2: Physics How does the intensity of a beam of radiation vary with the distance from the source? Why does this happen?The intensity of a beam of radiation will decrease as the distance from the source increases. This is because the beam spreads out so fewer photons hit each square metre. Some of the beam is also absorbed as it travels.
- 8P2: Physics What is ionisation? What types of electromagnetic radiation can cause it?Ionisation is where an electron is removed from an atom or molecule. Ultraviolet, x-rays and gamma rays can all cause ionisation.
- 9P2: Physics Why is being exposed to ultraviolet radiation from the Sun dangerous? How can you protect yourself?Ultraviolet radiation is ionising and can damage your cells, which can eventually kill the cells or cause cancer. You can protect yourself using physical barriers such as clothes and sunscreen to absorb the radiation.
- 10P2: Physics What does a radiographer do? Why do they need to wear lead aprons?Radiographers use x-rays to take images of patients. X-rays are ionising and can damage cells, which can lead to cell death or cancer. Lead is a dense material and absorbs the x-rays so lead aprons stop radiographers being exposed to the radiation.
- 11P2: Physics How does electromagnetic radiation cause heating? What affects the amount of heating produced?An object is heated when it absorbs electromagnetic radiation. The greater the intensity of radiation and the longer the exposure time, the greater the heating effect will be.
- 12P2: Physics How do microwave ovens protect people using the oven?They have metal cases and door screens that reflect or absorb microwave radiation, stopping it getting to out of the microwave oven.
- 13P2: Physics Why do some people believe that mobile phones could be bad for your health?Some microwaves are absorbed by water molecules, causing them to heat up. If this happened to cells in your head it could be dangerous. So some people think it is dangerous to use mobiles or live near mobile phone masts as they emit low intensity microwave radiation.
- 14P2: Physics Describe the greenhouse effect and how it affects the Earth's temperature.The Sun emits high frequency electromagnetic radiation which is absorbed by the Earth and re-radiated at a lower frequency. Greenhouse gases in the atmosphere absorb infrared emitted by the Earth and re-radiate it in all directions including towards Earth. This means the Earth's atmosphere acts as an insulating layer, which helps to keep it warmer than it would be.
- 15P2: Physics Why is the ozone layer important?Ultraviolet radiation is ionising and can damage the cells of living organisms. The ozone layer absorbs UV so helps to protect life on the Earth's surface from being exposed to too much ionising radiation.
- 16P2: Physics What type of electromagnetic radiation does the ozone layer absorb? What effect does this have on the layer?The ozone layer absorbs ultraviolet radiation which produces chemical changes in that layer of the atmosphere.
- 17P2: Physics Why does the Sun emit radiation with higher frequencies than the Earth?It's hotter - the higher the temperature of an object, the higher the frequency of radiation it will emit.
- 18P2: Physics How has the amount of carbon dioxide in the atmosphere changed over the past 200 years? What has caused this change?The concentration of CO2 in the atmosphere has increased a lot. This has been caused by an increase in the amounts of fossil fuels being burned as an energy source which releases CO2 into the atmosphere. Forests have been burnt or cut down to clear land which also releases CO2.
- 19P2: Physics Why did the amount of carbon dioxide in the atmosphere remain roughly constant for thousands of years?Carbon is released and removed from the atmosphere in the carbon cycle. The processes in this cycle balanced out for thousands of years so the level of carbon dioxide in the atmosphere stayed fairly constant.
- 20P2: Physics What processes removes carbon dioxide from the atmosphere? What processes release carbon dioxide into the atmosphere?Photosynthesis in green plants removes carbon dioxide from the atmosphere. Burning, decay and respiration all release carbon dioxide into the atmosphere.
- 21P2: Physics How could global warming cause the flooding of low lying land?The increase in temperature would cause the land ice to melt and ocean water to expand, causing sea levels to rise. This would lead to flooding of low lying areas. Increased rainfall will also cause flooding.
- 22P2: Physics Describe and explain how global warming could affect the weather across the world.The increase in temperature could change the weather patterns in many areas and cause more extreme weather e.g hotter droughts. An increase in temperature could cause conviction, which could lead to stronger winds so more extreme weather. It could also increase the amount of water vapour in the air.
- 23P2: Physics How could global warming affect food production?Climate change caused by global warming could make it impossible to grow food in some regions if it is too wet or too dry for crops to grow.
- 24P2: Physics Describe how a digital signal is produced by using an electromagnetic wave. How will the original signal be recovered after it has been received?Information is superimposed onto an electromagnetic carrier wave by switching the carrier wave on and off. This creates pulses of waves where 0 = no pulse and 1 = pulse. A digital receiver will decode these pulses to get a copy of the original signal when it is received.
- 25P2: Physics Why is it easier to remove noise from a digital signal than from an analogue signal?A digital signal can only take a small number of discrete values e.g 0 or 1, so even with the addition of noise it's still easy to see what the original was and recover it. Analogue signals can take any value so it's harder to identify the noise from the original in order to remove it.
- 26P2: Physics What are the differences between an analogue and a digital signal?An analogue signal can have any value in a certain range and it varies continuously. A digital signal can only have a small number of discrete values (usually two) e.g on and off, or 0 and 1.
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- Flashcards on P2: Physics Flash Cards, created by maisey_clark on 12/11/2014.
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