AQA AS Physics Definitions Test Questions And Answers

AQA AS Physics Definitions Test Questions And Answers Specific charge - ANSWER- the charge to mass ratio or charge in coulombs divided by the mass in kilograms Isotope - ANSWER- a nucleus with the same number of protons but different number of neutrons Hadron - ANSWER- a particle that experiences the strong nuclear force. Composite particles made of either qqq (baryons) or q anti-q (baryon) Antimatter - ANSWER- Particles with the same mass but opposite charge Photoelectric effect - ANSWER- the emission of electrons from metal surfaces by light of an appropriate frequency Photon - ANSWER- a discrete packet/quantum of electromagnetic energy Work function - ANSWER- the minimum energy required for an electron to escape from the surface of the metal Threshold frequency - ANSWER- the minimum frequency of a photon required to release electrons from the surface of a metal Electron volt - ANSWER- the energy given to an electron when it passes through a potential difference of 1 V Energy Level - ANSWER- Allowed/discrete energy of an atom or electron in an atom Ionisation energy of an atom - ANSWER- the minimum energy required to remove an electron from an atom in its ground state Excitation energy - ANSWER- the energy required to move an electron from a lower energy level to a higher energy level Line spectra - ANSWER- the characteristic wavelengths of light produced by individual excited atoms Longitudinal waves - ANSWER- direction of oscillation is parallel to the direction of wave travel. Wave travels with series compressions and rarefactions. Transverse waves - ANSWER- direction of oscillation is perpendicular to the direction of wave travel with peaks and troughs. Electromagnetic wave - ANSWER- a transverse wave, consisting of a changing magnetic field at right angles to a changing electric field Amplitude - ANSWER- the maximum displacement from the equilibrium position Frequency - ANSWER- the number of oscillations per second Wavelength - ANSWER- the shortest distance between two consecutive particles in a wave which are in phase Wave speed - ANSWER- the speed of energy transfer through the medium Diffraction - ANSWER- Diffraction is the spreading out of a wave as it passes through an aperture/around an obstacle. Polarised waves - ANSWER- electromagnetic waves where the oscillations are in one direction only that is 90° to the direction of wave travel Unpolarised waves - ANSWER- electromagnetic waves where the oscillations are in many directions Refractive index - ANSWER- the absolute refractive index of the substance is the speed of light in a vacuum divided by the speed of light in the substance, n = Vc/Vs Critical angle - ANSWER- the angle of incidence on a boundary between two media when the angle of refraction is 90° Total internal reflection - ANSWER- total internal reflection occurs when an EM wave goes from a more dense to less dense medium and the angle of incidence is greater than critical angle. All the light is reflected within the substance Step index fibre - ANSWER- there is a sudden change in refractive index between the core and the cladding Path difference - ANSWER- the difference in distance one wave has to travel to reach a point compared to another wave Superposition - ANSWER- when two or more waves of the same type meet at a point the resultant displacement of will be the sum of the individual displacements Stationary wave - ANSWER- a stationary wave is formed by two waves of the same frequency and similar amplitude travelling in opposite directions. There is no net energy transfer. Node - ANSWER- a point on stationary wave with zero amplitude Antinode - ANSWER- a point on stationary wave with maximum amplitude Fundamental frequency - ANSWER- the lowest frequency of a wave which will produce a stationary wave Coherence - ANSWER- coherent waves have a constant phase relationship and the same frequency Monochromatic - ANSWER- waves of only one frequency Fringe spacing - ANSWER- the distance between two consecutive maxima or minima in an interference pattern Electric current - ANSWER- the number of coulombs of charge passing a point per second (I=Q/t) Potential difference - ANSWER- the work done per unit charge when charges move from one point in the circuit to another (V=E/Q) Resistance - ANSWER- the ratio of the potential difference across a component to the current through it