Physics Paper One Flashcards
What are the different energy stores?
- Thermal
- Kinetic
- Gravitational Potential
- Elastic Potential
- Chemical
- Magnetic
- Electrostatic
- Nuclear
What is meant by energy lost from the g.p.e store?
What is meant by energy lost from the g.p.e store = Energy gained in the kinetic energy store.
Kinetic energy?
1/2 x Mass x Velocity²
Gravitational potential energy?
Mass x field strength x height
Elastic potential energy?
1/2 x spring constant x extension²
What is meant by specific heat capacity?
The amount of energy needed to raise the temperature of 1kg os substance by 1 degree.
Change in thermal energy?
Mass x specific heat capacity x temperature change
What does the conservation of energy principle state?
Energy can only be transferred, stored or dissipated but can never be destroyed or created.
What are the 2 ways of calculating power?
Energy ÷ Time
Work Done ÷ Time
What is conduction?
The process where vibrating particles transfer energy to neighbouring particles.
What is convection?
Where energetic particles move away from hotter to cooler regions.
How do you reduce unwanted energy transfers?
- Lubrication
- Insulation
What are the 2 ways of calculating efficiency?
Useful output energy transfer ÷ Total input energy transfer
Useful power output ÷ Total power input
What are some examples of non-renewable energy resources?
- Coal
- Oil
- Natural Gas
What are some renewable energy resources?
- The sun (solar)
- Wind
- Water waves
- Hydro-electricity
- Bio-fuel
- Tides
- Geothermal
How is wind power made? Advantages and disadvantages?
Each turbine has a generator in it, therefore the wind rotates it and produces the electricity. There's little pollution made (only when they are being built). \+ Renewable \+ No greenhouse gases produced - Noisy - Ugly - Initial costs are high
What is geothermal power? Advantages and disadvantages?
Produces energy from underground thermal energy stores. It is only possible in volcanic areas where hot rocks lie near to the surface. \+ Essentially free energy \+ Renewable - Expensive - Few suitable locations.
What is bio-fuels?
Renewable energy resources from plants or animal dung. These can be burnt to produce electricity. \+ Carbon neutral \+ Reliable - Costs are high - No space of water for other crops - Areas have been cleared for bio-fuels.
What is current?
The flow of electric charge.
What does a greater resistance mean?
The higher the resistance, the smaller the current that flows through (for a potential difference across the component)
How do calculate charge?
Current x Time
How do calculate potential difference?
Current x Resistance
What are ohmic conductors?
The resistance doesn’t change with current. At a constant temperature, the current flowing through an ohmic conductor is directly proportional to the potential difference across it.
What does ‘I-V Characteristics’ mean?
A graph which shows how the current flowing through a component changes as the potential difference across it is increased. Linear have a straight line.
What is current like in a series circuit?
The current is the same everywhere. i1 = i2
What is resistance in a series circuit?
It adds up R1+R2 = R total
What is the potential difference like in a parallel circuit?
The potential difference is all the same.
V1=V2=V3
What is current like in a parallel circuit?
It adds up
I1+I2= Itotal
What are the 2 types of electricity supplies?
a. c - alternating current
d. c - direct current
What is the UK mains supply like?
230V
50Hz
What are the 3 wires in plugs?
Neutral Wire (Blue) - This completes the circuit and carries away current. It is around 0V. Live Wire (Brown) - The live wire provides the alternating potential difference (at around 230V) from the mains supply. Earth Wire (Green/Yellow) - Protective. Stops the appliance from becoming live if there's a fault.
Energy Transferred (2)?
Power x Time
Potential Difference x Current
How is electricity distributed?
Through the national grid. It covers the UK and connects power stations to consumers.
What is static electricity?
Charges that are not free to move
In which direction do the arrows on electric field lines point?
They go from positive to negative.
How can a build up of static electricity cause a spark?
An electric charge builds on an object the potential difference between the object and the earth increases. If the potential difference gets large enough, so electrons can jump across the gap. Which is the spark.
What are the functions of step-up and step-down transformers?
To make it efficient for transmission and then bring it back down to save, usable levels at the other end.
How does the resistance of an LDR varies with light intensity?
In limited light, the resistance is highest.
The higher the light intensity the lower the resistance.
What happens to the resistance of a thermistor as it gets colder?
The resistance decreases as temperature increases.
What are the 3 states of matter?
Solid, Liquid and Gas
What are the arrangements of particles like in each state?
Solid: Strong forces of attraction, closely packed, vibrating and a fixed pattern.
Liquid: Weaker forces, close together but can move past each other
Gases: No forces of attraction, lots of energy, no pattern, free to move.
What is the formula for density?
Mass ÷ Volume
What’s the experiment to find the density of a liquid?
1) Place a measuring cylinder on a balance and zero the balance.
2) Pour 10ml of the liquid into a measuring cylinder and record the liquid’s mass.
3) Pour another 10ml into the measuring cylinder and record the total volume and mass. Repeat this until the measuring cylinder is full.
4) For each measurement use the formula to find density.
5) Take an average of your calculated densities.
What is internal energy?
The total energy that its particles have in their kinetic and potential energy stores.
What happens to the particles in a substance when that substance is heated?
It changes state
What are the 5 changes of state?
Melting Freezing Evaporating Condensing Sublimating
Explain the cause of the flat sections on a graph of temperature against time for a substance being heated?
When the substance is changing state it doesn’t change the temperature, therefore the lines are flat as there is no change in temperature.
Define specific latent heat?
The amount of energy needed to change 1kg of substance from one state to another without changing the temperature.
What is meant by the term specific heat of fusion?
Changing between a solid and a liquid.
For a fixed mass of gas at a constant temperature what is the relationship between pressure and volume?
Pressure and volume are inversely proportional
If a balloon containing a fixed mass of helium gas is moved from an area of high atmospheric pressure to one of low pressure. What will happen to the volume?
The balloon rises and the pressure outside decreases so the pressure outside the balloon decreases. This causes the balloon to expand until the pressure inside drops to the same as the atmospheric pressure.
How has the atomic model changed over time?
1804 John Dalton - Tiny spheres
100 years later J.J Thomson - plum pudding (electrons could be removed so spheres of positive charge with tiny negative electrons stuck in them)
1909 Rutherford - Nucleus.
Niels Bohr - Electrons on shells.
Who provided evidence to suggest the existence of the neutron?
James Chadwick
What happens if an atom loses one or more of its outer electrons?
It becomes a positively charged ion.
What is the activity of a source?
Half-life
Explain the dangers of a radioactive source with a long half-life?
The activity falls more slowly because most of the nuclei don’t decay for a long time - the source justs sits there releasing small amounts of radiation for a long time.
What is radiation dose?
The reaction dose tells you the risk of the harm to body tissue due to exposure to radiation. It is measure in sieverts.
Define irradiation and contamination?
Irradiation: when something is exposed to radiation
Contamination: consuming the radioactive material
How is radiation used in medicine?
Can be used to detect things like a thyroid gland.
What risks are there with using radiation?
- Can enter living cells and ionise atoms and molecules. Which can lead to tissue damage.
- Can cause cancer.
- Too high doses kill cells completely.
What is nuclear fission?
A type of nuclear reaction that is used to release energy from large and unstable atoms by splitting them into smaller atoms.
What is nuclear fusion?
Two light nuclei collide at high speed and join to create a large heavier nucleus.
What is a chain reaction?
A chemical reaction or other process in which the products themselves promote or spread the reaction.
What is the difference between nuclear fission and fusion?
They are the opposite.
What is an alpha particle?
2 neutrons and 2 protons (helium nucleus)
They don’t penetrate very far into materials and are stopped quickly, they are absorbed by a sheet of paper.
They are strongly ionising because of their size.
What are beta particles?
A fast moving electron released by the nucleus. They have no mass and a charge on -1. Moderately ionising. They penetrate moderately, and are stopped by a sheet of aluminium. For every beta particle emitted, a neutron in the nucleus has turned into a proton.
What are gamma rays?
Waves of electromagnetic radiation released by the nucleus. They penetrate far into materials without being stopped. They are weakly ionising.
