Flashcards
P2
Cards in this deck (21)
- 1When do you see things?You only see things when your eyes (detectors) absorb EM radiation called light.
- 2What are some of the things we see?Some of the things we see are light sources. They emit light by glowing hot.
- 3What is everything else that we see?Everything else that we see reflects light. Black objects don't reflect much light, they mainly absorb it.
- 4What do shiny objects do?Shiny objects reflect most of the light that falls upon them.
- 5What do all waves in the EM spectrum do?All waves transmit through a vacuum at 300,000 km/s.
- 6What do EM waves do?They transfer energy in packets called photons.
- 7What does the energy in a photon depend on?It depends on the frequency of the wave. Increasing the frequency of an EM wave increases the energy of its photons.
- 8What do solar cells do?Solar cells produce electricity. They work by absorbing EM radiation from the son. The solar cell transfers this energy to electrical energy.
- 9What depends on the waves intensity?The energy absorbed in each second from an EM wave depends on its intensity.
- 10What does this intensity depend on?It depends on the number of photons per second. Intensity increases with the number of photons.
- 11What does this intensity also depend on?It also depends on the energy transferred by each photon because intensity increases with energy.
- 12What is the energy of a wave?The energy of a wave is spread over an increasing area as it moves away from its source.
- 13What does this mean in terms of intensity?This means that the intensity of the wave decreases with increasing distance from its source.
- 14What do the photons of an ionizing radiation have?They have enough energy to ionize atoms or molecules.
- 15What can ionization of a molecule start off?It can start off a chemical reaction involving that molecule.
- 16What do radioactive materials emit?Gamma rays which pass easily through the human body.
- 17What do X-rays do?They pass through muscle but are absorbed by bone.
- 18What happens when cells absorb radiation?Cells are ionized or damaged when they absorb gamma or x-rays.
- 19What can the damaged cells do?They can either die or develop into a cancer.
- 20What do physical barriers do?They absorb some ionizing radiation.
- 21What are X-rays used for?They are absorbed by dense materials, so are able to make shadow pictures of people's bones or their luggage.
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- Flashcards on P2, created by khalidaa on 30/04/2015.
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- khalidaa · Apr 2015
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- Feb 19, 2016
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