A Level

CATHODE RAY TUBE – RAY OSCILLOSCOPE (C.R.O.)

The cathode ray oscilloscope consists of the following components: the electron gun; the deflecting plates; a fluorescent screen. The electron gun: the electron gun is the same as the basic electron gun but with a grid, which is connected to a negative potential. The...

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Uses of Radiation

Cancer treatment (radiotherapy) using gamma rays Tracers in the body to map internal structures Radioactive dating Detecting cracks or imperfections in structures Electron Volt – unit used in describing small energies to make them appear nicer

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Nuclear Equations

Proton and nucleon numbers are conserved Mass and energy are not conserved individually Mass-energy is conserved (E=mc2) Gamma rays can be emitted with alpha and beta particles

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Types of Radiation

Radioactive Decay – the process for a nucleus to achieve stability by decaying into a more stable form by either ejecting part of itself (through alpha-decay), converting neutrons to protons (betadecay) or ejecting excess energy (gamma decay). This process is...

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Ionisation

Radiation emitted by radioactive substances has a large amount of energy When radiation hits a neutral atom, some of this energy is passed to the atom This energy can cause an electron from the atom to escape, thus ionising the atom, leaving it with a positive charge;...

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Diffraction Grating

Diffraction Grating – an optical component with a periodic structure that diffracts light into several beams  

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Nuclear Physics

Isotope – an element that occupies the same place in periodic table but has a different number of neutrons. The number of protons and electrons are the same. E.g. Hydrogen has three isotopes: Protium (0 Neutrons), Deuterium (1 Neutron), Tritium (2 Neutrons  

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Young’s Interference

Coherent – waves emitted in the same phase from multiple sources An interference pattern is observed when two sources of wave of the same wavelength, frequency and amplitude are coherent and are emitted close to each other. This can also be done with a single wave...

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Polarisation

Polarisation – the process of transforming waves in which the vibrations travel in multiple planes, into waves with vibrations which travel on a single plane. Particles in a transverse wave are not restricted in their oscillation direction on the plane perpendicular...

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Superposition

Superposition – the resultant wave form when different waves meet at the same point in space at the same time is the sum of their individual displacements

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Stationary Waves

Stationary Waves – waveforms created through superimposing two identical progressive waves moving in opposite directions (incident and reflected). As they pass over each other, constructive and destructive interference occurs resulting in positions of maximum particle...

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Progressive Waves

Wave – a disturbance that moves itself and energy, but not matter from one place to another. They require a medium to transmit energy through. Particles in the medium do not move with the energy, instead they oscillate about their equilibrium position. Progressive...

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Wave Phase

Wave Phase ( ) – a measurement of how far out of step different points are on a waveform. Particles are considered to be in phase when they execute the same motion at the same time.  

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Experiment for determining Young’s Modulus

Method: Measure the original length of the wire (to the reference marker) with the ruler Measure the diameter of the wire with a micrometer Add a mass and calculate the weight of this mass Measure and record the extension of the wire with respect to the initial...

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Types of Solids

Crystalline Solids – the substances whose constituents are arranged in definite orderly arrangements. They possess characteristic geometric shapes and have sharp melting points. If cut or hammered gently they show a clean fracture among a smooth surface. Amorphous...

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Deformation of Solids

Elastic Deformation – when the material returns to its original length after the force is removed. This occurs when the material is extended anywhere up to the elastic limit. Plastic Deformation – when the material remains permanently deformed upon removing the load....

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Upthrust

Upthrust – the resultant force on an object equal to the weight of the displaced fluid. The net force is due to a higher pressure acting on the bottom of the object, than on the top.

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Complex Circuits

For complex circuits involving two or more batteries, the circuit should be separated into different loops. The direction of each loop will be the direction of the positive current. Any current going against the direction of the loop should be considered negative.

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Conductors

Conductors – materials with free charges. When a potential difference is setup across a conductor, the free electrons will experience a force and will accelerate. Non-Ohmic Conductor – a conductor which does not satisfy . Diode – a device that only lets current flow...

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Potential Dividers

Potential Dividers – two or more resistances in series connected to a source of fixed potential difference. The source potential difference is divided between the resistors, as they are in series with each other. A potential divider can be used to supply a potential...

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Electric Fields

Field – a region of space where a particle experiences a force Fundamental unit of charge: e = 1.9 x 10-19 C An electron has charge –e and a proton has charge +e All observable charges in nature are an exact integer multiple of e (as proven by Millikan)   Like...

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Momentum

Conservation of Momentum – occurs in a closed system, where the momentum before an event is equal to the momentum after it Closed System – nothing is allowed to enter or leave. There are no external forces acting on the system. Elastic Collision – when the sum of all...

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Work, Energy and Power

Energy – a quantity associated with an object that relates to its speed or position in space, relative to another object. A force is required to change the energy of an object Work (J) – the product of force moving through a displacement in the same direction as the...

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Projectile Motion

Projectile – anything that moves where the force of gravity is the only force acting Problems involving projectiles can be solved by considering the vertical and horizontal component separately The vertical velocity is accelerated due to gravity Find the range,...

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Quantities

Derived Units – all units for every physical quantity in Physics are made up of the SI Base Units, known as Derived Unit.s e.g. F = ma [m = kg, a = ms-2, F = kgms-2] Homogeneous Equations – an equation is homogeneous if the units are the same on each side of the...

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Experimental Uncertainty

Random Error – upon multiple measurements, will result in readings being scattered around the accepted value. This can be reduced by repeating and averaging results or by plotting a graph and drawing a line of best fit e.g. reaction time, temperature fluctuation,...

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