Energy production
Global thermal energy transfer
…emperature to rise: the greenhouse effect. Test Yourself Use flashcards to practise your recall. Flashcards Topics: Global energy transfer Levels: All Number of questions: 11 Mode: Normal …
Thermal
Heat transfer
…he Thermal concepts page for information about evaporation. Summary Conduction While all matter is capable of allowing heat transfer by conduction, it is fastest in solids, particularly in metals with delocalised electrons. When the end of a solid…
Mechanics
Potential energy
It might be better to call potential energy "positional energy" since it is the energy a body has due to its position. Consider lifting a pen from the floor to your desk. The overall change in potential energy is unrelated to the path you took, wheth…
Energy production
Energy sources
The picture reveals the source of almost all of our energy - the sun. This might be obvious for solar cells, but what's the link between the sun and other energy resources? Key Concepts Fuels A fuel is any substance that contains chemical or nuc…
Mechanics
Conservation of energy
Energy is always conserved, but to find out where it has gone we sometimes need to look inside matter. Macroscopic processes can lead to microscopic changes. Summary Mass pushed up a frictionless slope When work is done on a block on a slope it gains…
Atomic, nuclear and particles
Electron energy levels
When light emitted from low pressure gases is passed through a prism, a line spectrum emerges. This tells us that the energy associated with movements of electrons between energy levels is quantized. The similarity between this and the harmonics in…
Mechanics
Work and energy
In the previous topics of Forces and Conservation of momentum we learned that an understanding of kinetic energy was required to fully predict the outcome of a collision. In this section, we'll attempt to define energy (easier said than done - as…
Energy production
Energy from the Sun
20% of the world's deserts covered with solar panels would supply enough energy for present needs. Here we will learn the first half of a means to calculate this energy: the intensity of the light emitted from the Sun upon the Earth's surface…
Mechanics
Kinetic energy
…uvat equations can be applied: \(E_k ={1\over2}mv^2\) Test Yourself Use quizzes to practise application of theory. Kinetic energy 07/04/2016 [SLIDES]: Using the equation and concept of workdone = gain in KE …
Energy production
Energy to the Earth
…earn about Conduction and Convection. However, we have these covered in the heat transfer section. This is where we take the energy that is incident on the Earth from the Sun and consider what happens to it. Key Concepts Spheres and discs The Earth a…
Atomic, nuclear and particles
Nuclear stability and binding energy
Binding energy is not possessed by a nucleus, but instead is released when the nucleus formed. Binding energy is often wrongly defined as the energy that holds a nucleus together. The nucleus is held together by the nuclear force. Binding energy is t…
Oscillations and waves
SHM and energy
…ther it's a pendulum, a mass on a spring or an electrical oscillator, an oscillating system can be described in terms of energy changing from one form to another. Key Concepts Energy changes in a pendulum When a pendulum is released, EP is conver…
Options
Angular momentum and rotational kinetic energy
…of an explosion, where two objects begin to rotate simultaneously in opposite directions. Essentials Rotational kinetic energy Rotational kinetic energy is calculated as follows: \({E_\textrm{K}}_\textrm{rot}={1\over 2}I\omega ^2\) \({E_\textrm{…
Energy production
…the greenhouse effect results from greenhouse gases Key questions What does a power station do? Heat engines convert thermal energy into mechanical work. When water is boiled to produce steam, these gas particles exert a pressure on the walls of thei…
Thermal
Thermal concepts
…e: Average Ek Internal energy: Sum of Ek Heat: Is transferred to change temperature Macroscopic terms Mechanisms for heat transfer Conduction is the transfer of heat by molecules vibrating and colliding to pass Ek from one to another. This is comm…
Oscillations and waves
Waves
…ints between a node and antinode different All points within one wavelength out of phase All points between 2 nodes in phase Energy transfer No energy transfer Wave profile progresses Wave profile stationary Test Yourself Use flashcards to practise…
Energy production
Renewable sources I
…utral. Solar Solar heating is the use of the Sun's infrared radiation to directly heat household water. To optimise heat transfer, solar heating pipes are painted black, placed om the roof, and twisted into a large surface area. The photovoltaic…
Energy production
Nuclear power I
Present-day nuclear power relies on nuclear fission - that energy is released when a large, relatively unstable, nucleus splits into two, more stable nuclei. This is a consequence of binding energy in the nucleus. This energy can be used to heat wate…
Electricity and magnetism
Electromotive force (EMF)
A battery converts chemical energy to electrical energy. How it does this is one of the mysteries explained by Chemistry... or fairies! The electrical energy produced per unit charge is known as electromotive force. Be warned: while this sounds like…
Atomic, nuclear and particles
Fission
Nuclear fission is used today around the world to generate electricity in nuclear power stations. The binding energy curve explains why the process releases energy. Key Concepts If a massive nucleus splits into two, there is an increase in binding en…
Electricity and magnetism
AHL EM induction
Electromagnetic induction is the process by which kinetic energy is converted into electrical energy in the presence of a magnetic field. How can we determine the magnitude and direction of induced EMF? What is involved in the construction and operat…
Electricity and magnetism
AC generators
Most of the world's electrical power is generated using electrical generators. Generators convert rotational kinetic energy (usually powered by a turbine) into electrical energy using electromagnetic induction. Key Concepts Operation A basic AC g…
Atomic, nuclear and particles
Photoelectric effect and photons
…ric effect is indisputable evidence for the particle nature of light. Particles of light are discrete and named photons. The energy of a photon depends not on intensity but frequency. Key Concepts Photoelectric effect There is a significant body of e…
Is your teacher lying about electricity?
…ed me the question. I got the answer right :-) However I'm not going to change what I teach, the model we use to explain the transfer of energy works, it doesn't have to be true. I watched the video on youtube then read some of the comments. Derek is…
Atomic, nuclear and particles
AHL Quantum
…s maximum kinetic energy High energy interactions Photons with more energy than is required for the photoelectric effect can transfer energy and momentum to electrons through Compton scattering. Conservation laws suggest that the photons have momentu…
Options
Second law
…ngine. \(Q_\textrm{H} =W_\textrm{out}+Q_\textrm{C}\) A refrigerator or heat pump is the opposite. Work is done on the gas to transfer heat from a low temperature energy store to a high temperature store. \(W_\textrm{in}+Q_\textrm{C}=Q_\textrm{H}\) …
Electricity and magnetism
AHL Electric fields
…ld (C) \(V_e\) is the potential difference between the plates (V) \(d\) is the distance between the plates (m) Calculating energy changes The energy changes that take place in electric fields are between electric potential energy and kinetic energy…
Atomic, nuclear and particles
…ail the fundamental forces of nature Explain why a single quark hasn't ever been observed Discuss how nuclei can release energy to become more stable The Higher Level content includes the determination of the radius and exponential nature of deca…
Atomic, nuclear and particles
Fusion
The process of nuclear fusion can be explained using the curve of binding energy per nucleon against nucleon number. Key Concepts When two small nuclei fuse to make a bigger one, the binding energy per nucleon is increased. This means that energy is…
Options
AHL Stellar processes
…volution of different types of star, here we will dig a little deeper. Under what circumstances will a nebula collapse? What energy changes are happening during fusion beyond the main sequence? What happens to make a star die? And what does all of th…
Options
AHL Fluid dynamics
Fluid dynamics is the study of moving fluids. As with moving bodies, mass and energy are conserved leading to equations that can be used to determine unknown quantities. An understanding of fluid properties enables us to calculate drag forces and the…
Electricity and magnetism
Transformers
…ls Power transmission The process of transmitting electrical power from a generator to a town is optimised to reduce thermal energy losses. The main culprit is usually thermal energy loss in power lines, due to the size of the current. To reduce this…
Electricity and magnetism
Potential difference
Potential difference (also known as voltage) is the amount of energy converted to heat per unit charge passing between two points in the circuit. It is possible to add together potential differences due to conservation of energy. Summary A battery cr…
Electricity and magnetism
Internal resistance
All power supplies contain some internal resistance when current is flowing due to the thermal energy produced as charges move. If a battery with no internal resistance was short circuited by a wire of zero resistance where would the energy go? Some…
Mechanics
Collisions
Using the laws of conservation of energy it is possible to calculate the combined velocity of two astronauts colliding in space... ...in case that was on your bucket list :) You don't need to memorise everything on this page (you will always have…
Circular motion and gravity
…atellites stay in orbit even though they are not powered by anything Derive the relationship between gravitational potential energy and position for a non-uniform field Key questions What is the difference between the centripetal and centrifugal forc…
Electricity and magnetism
Electrical power
…aving no charge'. This is incorrect in physics, as charge is conserved and not used up. Instead, we are using electrical energy (the ability to make charges move!). We get billed for the units we consume of electrical power over a given time. Sum…
Thermal
Latent heat
It is clear that, to melt ice and boil water, you need to add heat... but where does that energy go? It seems to be hidden, hence the name latent heat. This is in contrast to sensible heat, where a temperature change is observed with the addition of…
Energy production
Renewable sources II
…rces: Hydroelectric Wind Solar (both direct heating and photovoltaic cells Key Concepts Hydroelectric power Infrared thermal energy from the sun drives the water cycle, causing rain to fall on mountains. Potential energy in the water can be converted…
Energy production
Nuclear power II
…used in nuclear weaponry. Essentials Neutron absorption When a neutron is absorbed by a uranium nucleus, it's binding energy per nucleon increases. This makes the nucleus too unstable and so it splits to release this energy. Moderation Fast…
Energy production
Power stations
…ll learn about the physics principles that govern the four key sections: Fuel Boiler Turbine Generator Key Concepts Specific energy is the ratio of the energy contained in a body to its mass, \(E\over m\). The unit of specific energy is J kg-1. Like …
Mechanics
Force vs displacement graphs
It is straightforward to calculate work done and energy changed using the equation when the force is constant. If the force varies, we can use a graph of force against displacement. Key Concepts Work done = force x distance. This is the same as the a…
Thermal
Particle model (kinetic theory)
All matter is made up of particles (particle model). Since particles are constantly moving (kinetic theory), we should be able to explain all the properties of matter in terms of particle motion. On this page, we will consider states of matter, force…
Exam questions
HL practice paper 2
…ion that applies for any value of angle. The identity that you must learn is: \(\tan \theta={\sin \theta\over \cos\theta}\) Energy transfers Kinetic energy (Ek) is due to movement, equal to the amount of work required to make a body move. \(E_k={1\o…
Atomic, nuclear and particles
Nuclear physics
…e and their properties Nuclear decay - calculating how the number of nuclei change over time Strong nuclear force - binding energy and mass defect Fission and fusion - processes and stability Key Concepts The nucleus Protons and neutrons All nuclei…
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