# Combined Science Physics 1

• Created by: Lilyk30
• Created on: 23-04-18 15:50
What is a system?
An object or group of objects
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What is specific heat capacity?
The amount of energy required to raise the temperature of one kilogram of the substance by one degree celcius
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What is power?
The rate at which energy is transferred or the rate at which work is done
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What is an energy transfer of one joule per second equal to?
One watt
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How can energy be transferred?
Usefully, stored or dissipated, but cannot be created or destroyed
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What happens to the energy transfers in a closed system?
There is no net change to the total energy
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What does energy wasted mean?
In all system changes, energy is dissipated so that it is stored in less useful ways
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How can you reduce unwanted energy transfers?
Lubrication, thermal insulation
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What does a higher rate of thermal conductivity result in?
Higher rate of energy transfer by conduction across the material
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How is the rate of cooling of a building affected?
By the thickness and thermal conductivity of its walls
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What are the main energy resources available for use on Earth?
Fossil fuels, nuclear fuel, biofuel, wind, hydro-electricity, geothermal, tidal, solar and waves
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What is a renewable energy resource?
One that is being or can be replenished as it is used
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What must a closed circuit have for an electrical charge to flow through it?
A source of potential difference
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What is electrical current?
A flow of electrical charge
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What is the size of electrical current?
The rate of flow of electrical charge
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What does the current through a component depend on?
Both resistance of the component and the potential difference across the component
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What is the current through an ohmic conductor directly proportional to?
The potential difference across the resistor
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What components change resistance with the current through the component?
Lamps, diodes, thermistors and LDRs
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As the resistance of a filament lamp increases, what else increases?
The temperature of the filaments
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How does the current through a diode flow?
In one direction only
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What are the two ways of joining electrical components?
In series and in parallel
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For components connected in series:
There is the same current through each component; the total potential difference is shared between the components; the total resistance of two components is the sum of the resistance of each component
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For components connected in parallel:
The potential difference across each component is the same; the total current is the sum of the currents through seperate components; the total resistance of two resistors is less than the resistance of the smallest resistor
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What is mains electricity?
An ac supply
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What does the UK's domestic electricity supply have a frequency of?
50 Hz and is about 230 V
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What colour is the live wire?
Brown
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What is the colour of the neutral wire?
Blue
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What is the colour of the earth wire?
Green and yellow stripes
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What does the live wire carry?
The alternating potential difference from the supply
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What does the neutral wire do?
Completes the circuit
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What is the earth wire?
A safety wire to stop the appliance becoming live
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What are everyday appliances designed to bring about?
Energy transfers
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What does the amount of energy transfers depend on?
How long the appliance is switched on for and the power of the appliance
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What happens when charge flows ina circuit?
Work is done
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What is the national grid?
A system of cables and transformers linking power stations to consumers
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What are step-up tansformers used for?
To increase the potential difference from the power station to the transmission cables
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What are step-down transformers used for?
To decrease the potential difference for domestic use
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When substances change state, what is conserved?
Mass
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What are changes of state?
Physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed
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How is energy stored inside a system?
By the particles that make up a system, called internal energy
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What is internal energy?
The total kinetic energy and potential energy of all the particles that make up a system
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What does heating do to a system?
By increasing the energy of the particles that make up a system which either raises the temperature or produces a state of change
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What does the increase in temperature of a system depend on?
The mass of the substance, the type of material and the energy input into the system
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What happens when there is a change of state?
The energy supplied changes the energy supplied changes the enrgy stored but not the temperature
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What is specific latent heat?
The amount of energy required to change the state of one kg of the substance with no change in temperature
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What is specific latent heat of fusion?
Change of state from solid to liquid
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What is specific latent heat of vaporisation?
Change of state from liquid to gas
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What does the temperature of gas relate to?
The average kinetic energy of the molecules
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What does changing the temperature of a gas held at constant volume change?
The pressure exerted by the gas
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What is the basic structure of an atom?
A positively charged nucleus composed of both protons and neutrons surrounded by negatively charged electrons
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What are energy levels?
Where the electrons are arranged at different distances from the nucleus
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How may the electron arrangements be changed?
With the absorption of electromagnetic radiation or by the emission of electromagnetic radiation
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What will a nucleus do to become stable?
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What is the random process of nucleus radiation called?
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What is activity?
The rate at which a source of unstable nuclei decay
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What is activity measured in?
Bequerels
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What is count rate?
The number of decays recorded each second by a detector
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What does an alpha particle consist of?
Two electrons and two protons
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What does a beta particle consist of?
A high speed electron ejected from the nucleus as a neutron that turns into a proton
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What does a gamma particle consist of?
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What does beta radiation do to the nucleus?
Doesn't change the mass but does cause the charge of the nucleus to increase
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What does the emission of a gamma ray do to the nucleus?
Nothing
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Yes
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What is half-life?
The time it takes for the number of nuclei of the isotope in a sample to halve; the time it takes for the count rate to fall half its initial level
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The unwanted presence of materials containing radioactive atoms on other materials
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What is the hazard from contamination?
The decay of contaminated atoms
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## Other cards in this set

### Card 2

#### Front

What is specific heat capacity?

#### Back

The amount of energy required to raise the temperature of one kilogram of the substance by one degree celcius

What is power?

### Card 4

#### Front

What is an energy transfer of one joule per second equal to?

### Card 5

#### Front

How can energy be transferred?