O/A Level Physcs

The Atom and the Quantum Notes: The electron doesn’t radiate light while it accelerates around the nucleus in a single orbit, but that radiation of light takes place only when the electron jumps orbit from a higher energy level to a lower energy level. Color depends on the (distance of) jump. Bohr’s views explained the regularities being found in atomic spectra. Summary of terms: Ritz combination principle: the theory that the spectral lines of the elements have frequencies that are either the sums or the differences of the frequencies of two other lines. de Broglie matter waves: the associated wave properties of all particles of matter. The wavelength of a particle wave is related to its momentum and Planck’s constant, l=h/momentum Shrodinger’s wave equation: the fundamental equation of quantum mechanics, which interprets the wave nature of material particles in terms of probability wave amplitudes. Correspondence principle : the rule that a new theory is valid provided t...

Reflection and Refraction Fermat’s Principle: Out of all possible paths that light might take, to get from one point to another, it takes the path that requires the shortest time. Law of Reflection: The angle of incidence equals the angle of reflection. Plane mirrors: The observer sees the image of a candle at a point behind the mirror. The light rays do not actually come from this point, so the image is called a virtual image. Causes of refraction: the bending is caused by a change in speed. Dispersion: Violet light travels about one percent slower in ordinary glass than does red light. Terms: Reflection: the return of light rays from a surface in such a way that the angle at which a given ray is returned is equal to the angle at which it strikes the surface. When the reflecting surface is irregular, light is returned in irregular directions; this is diffuse reflection. Refraction: the bending of an oblique ray of light when it passes from one transparent medium to anot...

Electricity The force between two electrically charged objects is F=(Kq1q2)/r^2 (r=distance, q=charges, k=proportionality constant) E = Elemental electric charge (-1.6 x 10-19 Coulombs) Conductor - allows electric charge to move thru it Insulator - materials in which the electrons are tightly bound E=F/q F=Eq   A=F/M=Eq/M   W=FD=EqD 1 Volt=1 Joule/1 Coulomb Ampere=Coulombs/Second (A=q/s) 1 Amp=6.25 x 1018 electrons/second 1 Amp(120V)=120W P=VI Electromotive Forces: Battery, Thermoelectric, Electromagnetism Fluorescent lights - 1 amp Motor starter - 100 amp Head L lights - 2 or 3 amp Resistance: Friction in a conductor, resists the movement of electrons, limits the amount of potential current that can pass. R=V/A A=current V=AR R=resistance A=V/R V=voltage What determines resistance? Type of material, shape and size ; like a hose-bigger means less R, longer means more R Electric current flows from high potential to low potential (volts) Thus in a...

Satellite Motion Summary of Terms: Satellite: A projectile or small celestial body that orbits a larger celestial body. Ellipse: The closed oval-like curve wherein the sum of the distances from any point on the curve to both foci is a constant. When the foci are together at one point, the ellipse is a circle. The farther apart the foci, the more eccentric the ellipse. Escape Speed: The speed that a projectile, space probe, or similar object must reach to escape the gravitational influence of the earth or celestial body to which it is attracted. Equations, Equivalences, and Concepts: The sum or KE and PE for a satellite is a constant at all points along its orbit. For a satellite in circular orbit, it is always moving perpendicularly to the earth’s gravitational field. Because a satellite moves at right angles to the earth’s gravitational field, no change in speed occurs - only a change in direction. The higher the orbit of a satellite, the less it’s speed and the longer i...

Sound Summary of Terms Infrasonic: A sound frequency too low to be heard by the normal human ear. i.e. below 20Hz Ultrasonic: A sound frequency to high to be heard by the normal human ear. i.e. about 20kHz Compression: Condensed region of the medium through which a longitudinal wave travels. Rarefaction: Rarefied region, or region of lessened pressure, of the medium throughout which a longitudinal wave travels. Reverberation: Re-echoed sound. Refraction: The bending of a wave through either a nonuniform medium or from one medium to another, caused by differences in wave speed. Forced Vibration: The setting up of vibrations in an object by a vibrating force. Natural Frequency : A frequency at which an elastic object naturally tends to vibrate, so that minimum energy is required to produce a forced vibration or to continue vibration at that frequency. Resonance: The result of forced vibrations in a body when an applied frequency matches the natural frequency of the bo...