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| Pregunta | Respuesta |
| What is ultraviolet light? | Electromagnetic waves with a higher frequency than visible light, used in the body to make vitamin D. |
| What is melanin? | A brown pigment found in the skin that protects against UV radiation. Having more melanin decreases the risk of skin cancer but makes it harder for the body to make vitamin D. |
| What does a source of radiation do? | Emits radiation, which then spreads out or 'radiates'. |
| How do we see colour? | Light is reflected off of objects that absorb some of the colours - eg a green bottle will absorb red but not yellow or blue light. |
| What is the ozone layer and what does it do? | The ozone layer is made up of ozone, or O3. It absorbs UV radiation, assuring that the earth isn't blasted with UV. |
| Why is there a hole in the ozone? | CFC's from fridges and aerosol cans escaped into the atmosphere, turning ozone back to oxygen. |
| Why is a hole in the ozone a really bad thing and what's being done? | The holes, which are over the poles, mean more UV can come through and heat the planet. CFC's are now carefully disposed of, but the ozone may take decades to heal. |
| What is a photon? | A 'packet' that carries energy. The higher the frequency of the radiation, the more energy in each photon. |
| If a photon has enough energy, such as in an X-ray photon, what will it do? | It will ionise atoms by knocking off an electron. |
| If a photon doesn't have much energy, such as in visible light, what is its main effect? | Heating, making atoms vibrate. |
| How do X-rays work? | X-rays are passed through the patient, hitting a detector on the other side. As bone is a stronger absorber than flesh, it absorbs more of the beam and shows up as a shadow. |
| What are gamma rays mostly used for in medicine? | Destroying cancerous tumours. |
| What are the risks of having an X-ray? | X-rays can cause cancer, especially in a fetus or a young child. |
| Can UV radiation cause cancer? | UV photons have enough energy to change atoms/molecules, causing chemical reactions in body cells, causing skin cancer. |
| What happens when a material absorbs microwave radiation? | It absorbs it and heats up - for example a potato in a microwave. |
| What are microwaves? | Non-ionising radiation that heats things. |
| Why do some people believe mobile phones are bad for you? | They heat your brain, slightly. But not as much as vigorous exercise. |
| What is infrared radiation? | Electromagnetic waves with a frequency below that of visible light. It's invisible but all objects that emit heat, even less than 0 degrees Celcius, emit radiation. |
| What is the greenhouse effect? | The warming of the Earth by its atmosphere, very similar to the effect of a greenhouse. |
| What are the greenhouse gases? | The minority gases that provide the greenhouse effect - carbon dioxide, methane and water vapour. |
| Describe how the greenhouse effect keeps the Earth's temperature steady? | Radiation from the Sun has a high frequency and passes through the atmosphere, whilst Earth radiation is absorbed and reflected back by the atmosphere. |
| Why is the Earth's average temperature increasing? | CO2, a greenhouse gas, is increasing in our atmosphere. More radiation is being reflected back to Earth. |
| Why is there more CO2 being released into the air? | We're more industrial and use more energy now - more electricity, cars, more objects etc. |
| What are the 4 predicted effects of climate change? | Extreme weather, rising sea levels, drought and desertification, spread of Malaria. |
| What continent produces the most CO2 per year? Why isn't this changed? | North America - because it's democratic, the government doesn't want to upset voters by harming the economy. |
| What is 'information'? | Images, sounds, text, numbers... all data that can be stored electronically. |
| What is a signal? | A carrier wave that's modified to carry information. |
| Describe analogue signal. | The amplitude varies continually, forming a curve on a graph |
| Describe digital signal. | The amplitude has to be 0 or 1, for example 0010011. This is binary code. |
| What 4 advantages do digital signals have over analogue ones? | Can be processed by microprocessors. Can be stored and take up little space. Can carry more information per second. Can be delivered with no loss of quality. |
| What is 'noise' in a signal? | Interference - as signals weaken noise is added in, and the interference can only be removed from a digital signal. |
| Why can digital signals be regenerated without noise? | The signal has to be 0 or 1, so the regenerator can tell it apart and correct it. |
| Why can't analogue signals be regenerated? | There's no way to tell what the original information was. When amplified, the noise is just amplified too. |
| What's the difference between perceived and actual risk? | Perceived risk is an estimate a person makes which is often inaccurate, whilst an actual risk is backed up by evidence. |
| In a scientific study, why do the sample groups have to be randomly picked? | To ensure an accurate spread over the whole population. Otherwise, results will be inaccurate. |
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