Physics Paper 1

• How to measure the resistance in a wire


  To measure the resistance in a wire you must:

  1) Place a wire on to a ruler and connect it to a circuit which measures its voltage and current

  2) Attach the crocodile clips to the wire at 0 cm and attach the other at 10 cm

  3) Switch the circuit on a measure the voltage and current

  4) Repeat this and increase the length of wire used by 5 cm and repeat the experiment
• How to measure specific heating capacity

  To measure specific heating capacity you must:

  1) Place a solid material into a solid block with a gap for the material and thermometer

  2) Measure the mass of the block before rapping it in insulator and measuring its original temperature

  3) have it all that the wire is connected to a power supply of 10 volts and turn on the stop watch

  4) In intervals of a minute measure the temperature found on the thermometer

  5) repeat it a few times
• As there is a voltage always in a live wire and you are in contact another surface, a current will flow through you and cause an electric shock.

  What will happen if you come into contact with a live wire? (Even if it is turned off)
• Earth wire


  The green and yellow wire in a circuit. It is for protecting the wiring., and for safety - it stops appliance casing from becoming live. It doesn't usually carry a current - only does so when there is a fault. This leads it to most of the time being 0 volts.
• Neutral wire

  The blue wire in a socket. It completes the circuit and is a neutral wire. It carries away the current and is at voltage of 0.
• Live wire


  The brown wire in a socket which provides an alternating potential difference of 230 volts.
• Wires in a socket

  The wire in a socket are the:

  1) Live wire

  2) Neutral wire

  3) Earth wire
• 230 Volts


  Voltage from the UK mains supply?
• The reason for stepping down the voltage on the national grid when providing electricity to our homes

  Stepping down the voltage when providing electricity to homes allows for the electricity to be safe with a lower potential difference, lowering the chance of electrocuting yourself.
• The advantage of a high voltage in the national grid

  A high voltage allows for the current to be reduced, which lowers the of energy lost by heat.
• How are transformers used in the national grid


  They are used to step up the voltage to 400,000 V and then to decrease the voltage back down when providing to the consumers home.
• What do step up transformers do?

  They increase the voltage and decrease the current. They have more coils in the secondary than primary.
• What do step down transformers do?

  They decrease the voltage and increase the current. There are more coils in the primary than the secondary.
• Wave power

  Uses lots of small water powered turbines located around the cost connected to a generator to conduct electricity producing zero emissions. However the problem is that they are unreliable and require the waves to not die down as well as sea bed habitats and only being producible around the coast.

  
• Hydro-electric power


  Requires the flooding of a valley by building a dam and allowing the water to go through via turbines producing no emissions to produce a current and electricity. However doing this causes a loss of land, vegetation and the release of green house gases methane and carbon dioxide.

  
• Geothermal energy


  Uses energy from volcanic area or where hot rocks lie close to the earth and is brilliantly reliable and can be used to generate electricity or heat buildings on their own. The problem is that there aren't enough suitable conditions to do this as well as the cost being to high to produce one.

  
• Solar cells


  Is used to generate electrical current from the sun light and produce zero emission. However they only work properly if it is sunny and cost a lot to initially buy them though afterward the cost is nothing.
• Wind power


  Is completed by the use of wind turbines to intersect the wind and convert the kinetic energy of the wind into electrical energy by a generator producing no emissions. The problem is that they are very noisy and can only produce energy if it is windy enough to turn there turbines.

  
• Renewable energy


  This is energy provided by natural resources that will never run out, example bio fuels, wind, water waves, the sun. Most of these do not cause any major damage to the environment. However the problem with them is that they do not deliver as much energy as fossil fuels currently and are unreliable as they mainly depend on specific weather conditions to work.
• Non-renewable energy


  Examples of these are fossil fuels and nuclear fuels. These are formed naturally over millions of year and are burnt to provide energy and damage the environment. The reason that they are Non-renewable is that they are being used up faster than they are being used. This means in the near future a replacement for these fuels is needed.
• Reducing energy transfer in buildings

  To reduce energy transfer transfer buildings have:

  Loft insulation- can reduce convection currents being created in the loft

  Drought excluders- incorporated around doors and windows reduces energy travel by convection

  Double-glazed windows- work in the same way as cavity walls they have an air gap between 2 sheets of glass so to prevent energy transfer by conduction
• Convection


  Is when energetic particles move away from hotter to cooler regions, this can happen in both gases and liquid. This is done by heating a gas or liquid until the thermal energy is transferred into kinetic energy for the particles. Because it a liquid/gas the particles are free to move, therefore the higher the kinetic energy the faster the particle. This leads to particles being further apart and making that liquid or gas less dense.

  
• Conduction


  The process where vibrating particles transfer energy to neighbouring particles. This is done by heating an object the particles transfer that heat energy into kinetic energy gradually leading to the particles in all of the object beginning to vibrate.

  
• Energy being wasted

  What may confuse you about the principle of energy transfer is that usually not all of the energy is transferred completely. This is not because the energy is destroyed but is because is has transferred into a different store of energy than what we wanted, this is called 'wasted energy.
• Conservation of energy principle


  The principle that 'energy can be transferred usefully, stored or dissipated, and it can never be destroyed or created
• energy transfer


  In energy when a system changes, energy is transferred either in or out of a specific object in the same or a different type of energy.
• System


  Is a posh way in saying an object. Closed versions of these objects are where no matter or energy can enter or leave leading to the net change in energy being 0.
• Different types of energy

  Some different types of energy are:

  Thermal energy

  Kinetic energy

  Gravitational potential energy

  Elastic potential energy

  Chemical energy

  Magnetic energy

  Electrostatic energy

  Nuclear energy
• Struggles with nuclear fusion

  The problem with nuclear is that scientist haven't found a way of using fusion for us to use. the temperatures and pressure needed for fusion to take place are so high that a nuclear reactor is very hard and expensive to build.
• Nuclear fusion


  Nuclear fusion is where 2 light nuclei collide at high speed and join, fuse, to create a larger, heavier nucleus. For example Hydrogen nuclei can fuse together to create a Helium nuclei. Nuclear fusion releases a lot of energy due to some of the light nuclei mass turning into energy released as energy, this energy is more than the amount gain able by fission

  
• Nuclear fission method

  To complete nuclear fission:

  Neutrons are added to the original radioactive isotope to make it more unstable

  The isotope splits to 2 new lighter elements as well as spitting out 2 or 3 neutrons on there own

  These neutrons will then randomly go and hit other isotopes, repeating the reaction.

  Due to this, this reaction can release a lot of of energy through gamma rays.

  
• Nuclear fission


  Is a type of nuclear reaction that is used to release energy from large unstable atoms, e.g. uranium or plutonium, by splitting them into smaller atoms.

  This is what is used in nuclear power plants but on a controlled scale. However this uncontrolled is what happens in nuclear weapons.

  
• Radio activity in medicine

  In medicine radio activity can be used to help the ill in hospitals. There are many examples such as:

  The injecting of the isotope iodine-123, which is absorbed by the thyroid gland just like the normal iodine-127, but it gives out radiation which can be detected to indicate wether the thyroid gland is taking in iodine as it should. The radiation released by this is always gamma as it passes easily through the body without causing ionisation. These isotopes have a short half life to allow for to get rid of the radioactivity once done so nothing bad happens to the patient.

  Radiotherapy use high doses of ionising gamma rays to directed accurately at cancerous cell to kill and get rid of them.
• Risks of radiation

  The risks of radiation depends on the amount of radiation dosage you receive:

  If the dosage is high there is a high tendency in that killing the cell completely, causing radiation sickness (vomiting, tiredness and hair loss) if a lot of cells all get attacked at the exact same time.

  If the dosage is low there is a tendency of minor to occur. This can cause cells to mutate and possibly divide uncontrollably. This is cancer.
• Contamination

  If unwanted radioactive atoms get inside or onto an object or person. These radio active then could decay, releasing radiation possibly causing harm, this is why gloves and tongs are used when handling radiation.
• Irradation


  Is when an object or person is exposed to radio activity. This does not make something radio active. Lead lined boxes, staying behind barriers are ways of reducing irradiation.
• background radiation

  Low level radiation released naturally by the environment. This come from:

  Unstable isotopes in things such as air, food, building materials and rocks

  Radiation from space, cosmic rays from the sun, this doesn't really affect us as the earth has an atmosphere

  Human activity, eg: nuclear explosions or nuclear waste.
• Half life


  The time taken for the number of radio active nuclei in an isotope to halve. By 'half' it means once 1 half life has taken place the 2nd half life is half the first half life, a quarter of the original, etc.
• Gamma decay


  These rays are a way of getting rid of excess energy from the nucleus. This means that there is no change to the atomic mass or number of the atom.
• Beta decay


  When these isotopes decay occurs, a neutron in the nucleus turns into a proton and releases a fast moving electron (the beta particle). The number of protons in the nucleus has then increased by 1 and the mass satya the same.