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31 Cards in this Set
- Front
- Back
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Capacitance |
The charge stored per unit potential difference across a capacitor |
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Time constant |
The product of capacitance and resistance, CR, for a capacitor - resistor circuit - equal to the time taken for the pd to decrease to e^-1 of its initial value when the capacitor discharges through a resistor |
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Electric field strength |
The force experienced per unit positive charge at that point |
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Coulombs law |
Any two point charges exert an electrostatic force on each other that is directly proportional to the product of their charges and inversely proportion to the square of their separation |
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Electric potential |
The work done by an external force per unit positive charge to bring a charge from infinity to a point in an electrical field - unit volt |
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Magnetic field lines |
Lines of force drawn to represent a magnetic field pattern |
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Magnetic flux |
The product of the component of the magnetic flux density perpendicular to a given area and that cross sectional area |
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Magnetic flux density |
The strength of the magnetic field - defined by the equation F/IL - symbol B, unit tesla T |
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Magnetic flux linkage |
The product of the number of Turns in a coil N and the magnetic flux |
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Faradays law |
The magnitude of the induced emf is directly proportional to the rate of change of magnetic flux linkahe |
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Lenzs law |
The direction of the induced emf or current is always to oppose the charge producing it |
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Strong nuclear force |
One of the four fundamental forces in nature, acting on hadron and holding nuclei together |
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Hadron |
A particle or antic particle that is affected by the strong nuclear force, and, if charged, by the electromagnetic force |
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Lepton |
A fundamental particle or antiparticle that is not affected by the strong nuclear force |
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Quark |
An elementary particle that can exist in six forms and join with other quarks to make up hadrons |
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Radioactivity |
The process by which unstable nuclear split, or decay, emitting ionising radiation |
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Activity |
The rate at which nuclei decay or disintegrate in a radioactive source, measured in becquerels (Bq) or decays per second |
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Half life |
The average time it takes for half the number of active nuclei in a sample of an isotope to decay |
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Carbon dating |
A method for determining the age of organic material, by comparing the activities, or the ratios of carbon14 to carbon12 nuclei of the dead material and similar living material |
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Annihilation |
The complete destruction of a particle and it's antiparticle in an interaction that releases energy in the form of identical photons |
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Mass defect |
The difference between the mass of a nucleus and the mass of its completely separated constituent nucleons |
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Binding energy |
The minimum energy required to completely separate a nucleus into its constituent protons and neutrons |
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Binding energy per nucleon |
The binding energy divided by the number of protons and neutrons in the nucleus; the greater the binding energy per nucleon, the more tight bound are the nucleon within the nucleus |
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Nuclear fusion |
A process in which two smaller nuclei join together to form one larger nucleus |
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Nuclear fission |
A process in which a large nucleus splits into two smaller nuclei after absorbing a neutron |
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Attenuation |
The decrease in the intensity of electromagnetic radiation as it passes through matter or space |
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Photoelectric effect |
The emission of photoelectrons from a metal surface when electromagnetic radiation above a threshold frequency is incident on the metal |
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Piezoelectric effect |
The production of an emf by some crystals such as quartz, when they are compressed, stretched, twisted or distorted |
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Acoustic impedance |
The product of the density p of a substance and the speed c of ultrasound in that substance, symbol Z - unit kgm^-2s^-1 |
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Acoustic matching (impedance matching) |
The use of two substances with similar acoustic impedance to minimise reflection or ultrasound at the boundary between them |
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Doppler effect |
The change in the frequency and wavelength of waves received from an object moving relative to an observer compared with what would be observed without relative motion |
