Physics Paper One
Energy
Electricity
Particle Model Of Matter
Atomic Structure
States of Matter
Energy Sources
Renewables: Energy sources that are sustainable, infinite & replenish in the short term
Non-Renewables: Energy sources that are unsustainable, finite and do not replenish
Fossil Fuels: Mined resources that are burned to generate electricity
Nuclear Energy
Coal
Oil
Natural Gas
Biomass energy
Water-based
Unreliable
Geothermal energy: Cool water is pumped underground in volcanic areas, and the resulting steam is used to rotate a turbine
Hydroelectric Power [HEP]
Tidal Energy
Wave energy: The energy from waves rotates a turbine
Solar Energy
Wind energy
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Doesn't produce much energy
Releases greenhouse gases (CO2 & CH4)
Contributes to climate change
The Nature of Energy
The 7 Energy Stores
Kinetic Store: The energy of a moving object (Accelerating, decelerating etc.)
Chemical Store: The energy of reacting chemicals (Fuels, batteries etc.)
Gravitational Potential Store: The energy stored by an object with mass at an altitude within a gravitational field
Magnetic & Electrostatic Stores: The energy when magnetic or electrical fields overlap
Nuclear Store: The energy when the nuclei of atoms join or separate (Nuclear plants, stars)
Elastic Potential Store: The energy of an object that is being elastically deformed (Compressed, squeezed, stretched etc.)
Thermal Store: The energy of something that has a temperature (Warm, hot & cold) [AKA not at absolute zero]
Four Energy Transfer Methods
Heat Transfer
Mechanical Transfer (Forces)
Electrical Transfer
Radiation Transfer
Equation for Kinetic energy: Eₖ=½mv²
Kinetic Energy = 0.5 x Mass x Velocity x Velocity
Joules = 0.5 x kilograms x metres/second x metres/second
Equation for change in energy during a temperature change: △E=mc△θ
Change in Energy = Mass x Specific heat capacity x change in temperature
Joules = kilograms x joules per kilogram per degree centigrade x degrees centigrade
Specific heat capacity: The energy required to raise the temperature of one kilogram of a substance by one degree centigrade
Equation for Elastic Potential Energy: Eₑ=½ke²
Elastic Potential Energy = 0.5 x Spring Constant x Extension x Extension
Joules = 0.5 x Newtons per metre x metres x metres
Work done Equations
Work Done = Potential difference x Charge
Joules = Volts x Coulombs
Work Done = Force x Distance
Joules = Newtons x Metres
Work Done = Spring Constant x Extension
Joules = Newtons per metre x metres
Equation for Gravitational Potential energy: U=mgh
Gravitational Potential Energy = Mass x Height x Gravitational Field Strength
Joules = kilograms x metres x newtons per kilogram
Gravitational Field strength on Earth is
9.81 N/kg
An Energy System is a group of objects with the ability to "do work"
Power is a measure of how quickly an object transfers energy
Power is measured in Watts. A single Watt is equivalent to one Joule per second of transferred energy
Equations for calculating Power:
Power = Energy / Time
*Watts = Joules / Seconds)
Power = Potential Difference x Resistance
Watts = Volts x Ohms
Conservation of Energy
The Law of Energy Conservation:
Energy can be neither created nor destroyed, but merely stored, transferred & dissipated
In a Closed Energy System neither mass nor energy can escape, so their total values always remain the same
When energy is transferred between stores & objects, some energy is wasted. This wasted energy dissipates into the environment as Thermal energy.
Energy Efficiency is a term used to describe how much energy an appliance uses usefully compared to how much it wastes
Equations of Energy Efficiency:
Efficiency = (Useful Energy output / Total Energy Input) x 100
Percentage = (Joules / Joules) x 100
Efficiency = (Useful Power Output / Total power Input) x 100
Percentage = (Watts / Watts) x 100
Reducing Wasted Energy
Materials with a high thermal conductivity (Such as bricks, wood, concrete & glass in housing) loses thermal energy very quickly, as they transfer energy at a higher rate
Materials with a low thermal conductivity lose thermal energy very slowly, as they transfer energy at a slower rate. These materials are called insulators
Lubrication (Reduces friction)
Double-Glazed Windows (Windows have an insulating layer of air between panes, reducing heat loss)
Foam-Filled Wall Cavities (Cavities in the wall filled with foam form an insulating barrier)
Fibreglass in lofts (Thermally insulates roofing)
Liquids
Freezing
Solids
Melting
Evaporation
Gases
Condensation
Sublimation
Deposition
Gases
Liquids
Solids
The Most Dense State
The State with the lowest volume
Particles are in a uniform arrangement
Particles Vibrate in Fixed Positions
Denser than gases, less dense than solids
Greater volume than solids, Less volume than gases
Particles are in Constant Motion
Particles move Relative to one another
There are exceptions to this. For example, Ice is less dense than water, and floats
The Least Dense state
The State with the greatest Volume
Particles move rapidly & randomly, with different speeds & directions
State Changes
When a state change occurs, Mass is conserved
State changes are Reversible
Physical Changes
Latent Heat
Equation for Latent Heat: E=mc
Energy = Mass x Latent Heat
Joules = kilograms x Joules per kilogram
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The Latent Heat of an object is the amount of energy required to change an object's state of matter without affecting its temperature
Energy Transfers
Temperature Change
Internal Energy
An object's Latent Heat of Fusion is the amount of energy required to change it from a solid to a liquid & vice versa
An object's Latent Heat of Fusion is the amount of energy required to change it from a solid to a liquid & vice versa
The Internal energy of a system is the energy stored by the particles, atoms & molecules of the objects in that system
Equation for Internal Energy:
Internal Energy = Kinetic Energy + Potential Energy
Density
Equation for Density:
Density = Mass / Volume
Kilograms per metre cubed = kilograms / metres cubed
To calculate the density of an irregular object
Weigh the Object's mass
Place the irregular object in a container filled to the capacity with water
The volume of the displaced water is equal to the volume of the irregular object
Use the calculation for density to work out the density of the object
Density is a measure of how closely packed together atoms in a material are
Heating an object raises its internal energy
When an object's internal energy is changed, its temperature either rises or it changes state
Gases
Gas Motion
Gas Pressure
The phenomena of gas particles moving randomly is known as Brownian Motion
When gases are heated, their particles move faster
This means they collide with the walls of their container more often with a greater force
This either causes the container to expand, or the pressure on its walls to increase
Atoms, Ions & Isotopes
Atoms & Nuclear Radiation
Hazards & Uses of Radioactive Emissions
Nuclear Fusion & Fission
Atoms
Nucleus: Contains particles called Protons & Neutrons (Both of which are called Nucleons)
Neutrons
Zero Charge
A Relative Mass of One
Orbitals: Orbitals are levels of energy surrounding the nucleus, and they house orbiting electrons
Protons
A Relative Mass of One
Electrons
A Charge of -1
An Electron's mass is negligible
The Diameter of an Atom is 2x10⁻¹³m
The radius of the nucleus is 0.0001% the size of the atom's radius
99% of an atom's mass is in the nucleus
Orbitals closer to the nucleus can only hold a certain number of electrons, and the number an orbital can hold increases as it get further away:
First Orbital: 2 Electrons
Second Orbital: 8 Electrons
Third Orbital: 8 Electrons
Electrons are able to absorb electromagnetic radiation and rise to a higher energy level. They can also emit that radiation and fall to a lower energy level
The number of protons in an atom is equal to the number of electrons
Therefore, atoms has no overall charge
A Charge of +1
Atoms of the same element have the same number of protons (Their Atomic Number)
In a standard Atom, the number of protons in the nucleus is equal to the number of neutrons
The total number of Nucleons in an atom is its Mass number
Isotopes: Isotopes are atoms of the same element with different atomic masses (i.e. an atom with a different number of neutrons to protons)
Example:
Lithium 6: Has 3 protons & 3 neutrons
Lithium 7: Has 3 protons & 4 neutrons
Ions: Atoms that have lost or gained one or more electrons are called Ions.
An Ion that has lost electrons becomes Positively Charged
An Ion that has gained electrons becomes Negatively charged
Atoms become ions in order to gain a full outer shell
Development of the Model of the Atom
500 B.C. Ideas of the Atom:
- Small, indivisible spheres of solid matter
- Comes from Amotos (Greek Democritus)
1808: John Dalton
- Atomic Theory: Different elements bond to form compounds
1869: Dimitri Mendeleez
- Designed the first periodic table
- Arranged in increasing atomic mass
- Left gaps for undiscovered elements
1897: J.J. Thomson
- Discovered the Electron (Proved atoms are divisible)
- Created the Plum Pudding Model
The Plum Pudding Model:
The Plum Pudding model theorised atoms consisted of a ball of positive charge containing embedded electrons of negative charge
1911: Ernest Rutherford:
- Tested the Plum Pudding Model
- Discovered the Atom's Nucleus (Dense core of positively-charged mass)
- Most of the Atom is empty space
Rutherford's alpha scattering experiment
Rutherford fired alpha particles at a thin sheet of gold foil.
- Most of them passed through the empty space
- However, some rebounded when they collided with the nucleus (Alike charges repel)
1913: Niels Bohr
- Suggested electrons orbit the nucleus
Rutherford-Bohr Model
The Rutherford-Bohr Model combined the findings of Rutherford & Bohr to produce a diagram with a positively-charged nucleus orbited by negatively-charged electrons
1932: James Chadwick
- Discovered the neutron
- The Atom's mass was double that of what it should have been, were it composed solely of protons
Alpha Particle: A Particle consisting of two protons & two neutrons (A Helium Nucleus)
Radioactive Decay: Unstable atomic nuclei can stabilise by releasing radiation
The Rate at which this happens is called (Radioactive) Activity, and is measured in Becquerels
The Count rate of a radioactive material is the number of decays that occurs per second, and can be measured with a Geiger-Muller Tube
Alpha Decay: An unstable nucleus dispels an alpha particle to stabilise
Beta Decay: An Unstable atom splits a neutron into a proton & an electron, and the resulting electron is dispelled to stabilise
Gamma Decay (: An Unstable atom dispels electromagnetic radiation
Mass number decreases by 4
Atomic number decreases by 2
Forms a new element
Neutron Decay: An Unstable atom decays and expels a neutron to stabilise
Atomic Number increases by 1
Forms a new element
Has the lowest penetration power (6-8cm)
Stopped by a few sheets of paper
Is the most ionising radiation
Alpha particles can draw electrons from other atoms
In Living cells, this can damage DNA & lead to caner
Has a moderate level of penetration power
(1-2m)
Can pierce paper but is stopped by a thin aluminium sheet
Has a moderate level of ionising power
Is the least ionising radiation
No mass or charge change
Has the highest penetration power (300-500m)
Only stopped by a thick lead slab or several metres of concrete
It cannot be predicted which or when specific nuclei will decay. However, it can be predicted when half of a radioactive sample has decayed.
Half-Lives: A Half-life is the time taken for the unstable nuclei in a radioactive isotope to half
Radioactive Contamination & Irriadation
Radioactive Contamination: Contamination is when something contains or is in direct physical contact with something radioactive
Radioactive Irradiation: Irradiation is when something is only exposed to the radioactive emissions of a radioactive substance. This does not mean an irradiated object is radioactive itself
Objects remain contaminated until the source of contamination is removed or it decays naturally
Required Practicals
Specific Heat Capacity
Methodology
Equipment:
- Thermometer
- Block of Material (One kilogram)
- An Immersion heater
- A Joulemeter
- A power source
- Insulation
Electrical Component Diagrams
Particles are widely spread without a pattern
Particles are Closely packed together
- Take a block of material with two holes (One for heater, one for thermometer) and warp it in insulation (leaving the holes open)
Thermal Insulation
Density
Resistance
I-V Characteristics
- Place the thermometer in one hole, and the immersion heater in the other
- Record the ambient starting temperature
- Turn on the heater
Resistors
Basic Components
Resistor (Ohmic)
Variable Resistor
Light Dependent Resistor (LDR)
Thermistor
Switch: Opens and closes the circuit
Cell: Acts as a source of Voltage
Battery: Is multiple cells adjacent to one another to provide a greater voltage
- Start the timer and record the temperature shown by the thermometer every minute (or two minutes)
- Use the mass, energy transfer shown on the joulemeter and change in temperature to work out the specific heat capacity of the block
Accuracy
Reliability
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Equipments
Diodes
Light-Emitting Diode (LED): Similar to the diode, except it emits light
Diode: Only allows current to flow through it in one direction
Measuring Components
Ammeter: Measures the current in a circuit. Placed in Series
Voltmeter: Measures the potential difference in a circuit, before and after a component. Placed in Parallel
