G485 Flashcards
What is the absorption spectra of a gas?
A spectrum of dark lines across a pattern of spectral colours produced when light passes through a gas and the gas absorbs certain frequencies.
What is acoustic impedance (Z)?
The property of a metal which determines the intensity of ultrasound refracted at a boundary with another material.
What is radioactive activity?
The number of radioactive decays per unit time. Measured in becquerels (Bq)
What is an alpha particle?
A particle comprising of two protons and two neutrons ejected from the nucleus during radioactive decay
What is the amount of a substance?
An SI quantity, measured in moles
What is annihilation?
The process where a particle and antiparticle interact and their combined mass is converted into energy using E=mc^2
What is an antiparticle?
A particle of antimatter that has the same rest mass but, if charged, equal and opposite charge to its corresponding particle, e.g the positron is the antiparticle to an electron
What is an astronomical unit?
The average distance from the earth to the sun.
1 AU = 1.496x10^11m
What is the attenuation coefficient?
A constant used to calculate the intensity of X-Rays as they pass through a material.
What is a baryon?
A particle consisting of three quarks (e.g a proton or neutron)
What is the baryon number?
A property of baryons and quarks that is preserved in particle interactions
What is a becquerel?
A unit of activity, one becquerel is 1 radioactive decay per second.
What is beta decay?
When a neutron breaks down into a proton under the influence of the weak nuclear force it emits a beta particle and an antineutrino
What is a beta particle?
A high speed electron emitted from the nucleus during beta decay
What is the Big Bang theory?
The theory that the universe was created from nothing from a single point.
The universe was much hotter, smaller and denser. Then it expanded.
What are binary stars?
Two stars in orbit around their common centre of gravity.
What is the binding energy per nucleon?
The average energy required to remove a nucleon from the nucleus.
What is a black hole?
The remnants of the core of a very large star after it has gone supernova. It has infinite density and a gravitational field so great that even light can’t escape.
What is the Boltzmann constant? (k)
A constant used when dealing with gases relating the temperature of the gas to the average kinetic energy of the particles in the gas.
It can be thought of as the gas constant for a single molecule.
k=1.3807x10^-23 JK-1
What is a ‘bottom’?
A type of quark.
State Boyle’s Law
The volume of a fixed mass of gas is inversely proportional to the pressure exerted on it provided temperature remains constant.
What is Brownian motion?
The random movement of small particles when suspended in a liquid or gas.
What is Capacitance (c)
The charge stored per potential difference as given by C=Q/V.
Measured in Farads, F.
What is a capacitor?
An electrical component designed to store charge.
What is capacitor discharge?
Connection a charged dalai for across a resistor and so enabling the charge to flow from one plate to another.
The charge remaining decays exponentially.
What is the centripetal force?
The resultant force on an object acting towards the centre of the circle which is causing it to move in a circular path