Flashcards
OCR Physics P4 Revision
Flashcards do conjunto (26)
- 1Which radioactive materials are commonly used in smoke alarms and what do they emit?Uranium 241, americium and others and they emit alpha
- 2What does static mean?Stationary
- 3Name the charges of each : Proton, Electron and NeutronPositive protons
Negative electrons
Neutral neutrons - 4Electricity take the path of the least...Resistance
- 5How does static electricity work? Use the terms; electrons, positive charge, negative charge and attractionOne substance gains an electron from another and the previously neutrally charged substances become oppositely charged and hence attract.
- 6Where are the following placed in a circuit and why : Ammeter, voltmeterAmmeter in the series as it always measures the current
Voltmeter in parallel to the component being measured as it measures potential difference - 7What colour are the earth, live and neutral wires in a plug
- 8what is the formula for calculating resistance?Resistance = voltage/current
- 9Does a fuse actually blow? If not what does it actually do and why?It melts if the current in the circuit is above the capacity of the fuse.
- 10Define ultrasoundSounds with a higher frequency than 20 000 Hz
- 11What is the name of the other type of sound outside our hearing range and what frequency does it have?Infrasound and it has a frequency of 20 Hz and below
- 12Name 3 uses of ultrasoundFoetus imaging
Breakdown of kidney stones
Sonar
Bone scans - 13What is alpha and what is its charge?A helium nuclei and a +2 charge
- 14What is beta and what is its charge?A high speed electron with a -1 charge
- 15What is gamma radiation and what is its charge?EM radiation and has a charge of 0 (neutral)
- 16Define half lifeThe time required for half the nuclei in a isotope to undergo radioactive decay
- 17What type of curve is seen on radioactive decay graphs and why?Exponential curves because radioactive decay is a spontaneous process so it can go on indefinetly
- 18What is ionisation?The process in which an atom gains or loses electrons to form an ion.
- 19What is the charge of an ion?positive or negative
- 20What type of reaction is nuclear fission?A chain reaction
- 21How do CT scanners work?A series of x-rays are fired and then received on the other side of a tube which moves along the body and from this you can image what the x-rays passed through like the thickness of the tissue.
- 22Why are high doses of radiation often safer than lower ones?Because they mutate and kill the mutated cells whereas lower doses will mutate the cells and leave them alive in the body which can cause cancer.
- 23How do radioactive tracers work?They detect abnormalities in the body and are attracted and absorbed by the damaged areas. They emit gamma which means that it can leave the body and be detected by machines. They need a short half life so that they don't stay in the body too long.
- 24Where does nuclear fusion occur naturally?In a stars core
- 25Why is fusion good?It releases a lot of energy and the products are not radioactive.
- 26Why don't we use nuclear fusion?Because it is currently infeasible on earth as it requires a very high temperature. Cold fusion has allegedly been performed once on earth and is currently being studied.
Informações
- Descrição
- OCR Physics P4 Revision cards
- Criado por
- Dan Allibone · mai 2015
- Atualizado
- 1 abr 2018
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