# GCSE Physics P3 (OCR)

Flashcards by Usman Rauf, updated more than 1 year ago More Less Created by Josh Price about 6 years ago Copied by Usman Rauf about 6 years ago
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### Description

GCSE Physics Flashcards on GCSE Physics P3 (OCR), created by Usman Rauf on 04/16/2015.

## Resource summary

 Question Answer What are the main primary energy sources that humans use? Fossil fuels (Oil, Coal, Gas) Nuclear Fuels Biofuels Wind Power Wave Power Radiation from the Sun Why is electricity called a secondary energy source? Because it must be generated using a primary energy source. What is the definition of a primary energy source? An energy source which is found or occurs naturally. How do power stations contribute to climate change? They burn fossil fuels, which produce carbon dioxide. What happens when electric current passes through a component? Energy is transferred from the power supply to the component and the environment. What is power a measure of? The rate at which an appliance transfers energy each second. What is the equation for calculating the amount of energy transferred? Power (W, kW) x Time (S, H) What is the equation for calculating power? Voltage (V) x Current (A) What does a domestic electricity meter measure energy transfer in? Why? Kilowatt hours (kWh) A joule is a very small amount of energy. How do you calculate the cost of energy? Number of units used (kWh) x Price of one unit (p per kWh). How do you calculate the efficiency of an electrical appliance? Energy (or power) usefully transferred ---------------------------------------------------- Total energy (or power) supplied x 100 How could energy usage be reduced in a personal context? - Use public transport - Waste less food - Eat less meat - Wear a jumper How could energy usage be reduced in a national context? - Insulate homes - Build more efficient power stations Why is electricity convenient? It is easily transmitted over distances and it can be used in many ways. What is mains electricity produced by? Generators How do generators produce electricity? A magnet is spun near a coil of wire, which produces an alternating current. How does the size of the current produced by a generator impact the amount of primary fuel it uses? The bigger the current, the more primary fuel it uses every second. What happens in a power station? A primary energy source is burned to boil water and make high pressure steam. The steam passes through a turbine, which rotates the generator to produce electricity. What type of waste is formed by a nuclear power station? Nuclear Waste What does radioactive waste emit? Ionising radiation What happens with increased exposure to ionising radiation? Damage to living cells increases eventually leading to cancer or cell death. What is the distinction between contamination and irradiation by a radioactive material? Contamination occurs when radioactive material land on or gets inside something. Irradiation is exposure to ionising radiation. Why is contamination more dangerous than a short period of irradiation? Because contamination leads to long term irradiation, which can cause cancer or kill cells. What are the benefits of nuclear power? - Yields more than the same amount of fossil fuel. - Produces less waste. Doesn't burn fuel, so no CO2 is produced. What are the risks of nuclear power? - It will increase the amount of irradiation. - Nuclear waste is radioactive for decades. What is the mains electricity voltage to our homes? 230 Volts Why is electricity distributed at high voltages across the National Grid? It reduces energy losses because the higher the voltage, the smaller the current needed for the same power output. With a smaller current, less energy is lost due to heating in the wires.

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