hl definitions Flashcards
angular frequency (ω)
the angular speed that an object undergoing uniform circular motion would have were it to match an object undergoing simple harmonic motion
critical damping
damping where the simple harmonic motion stops the first time the object passes through the equilibrium position
damping
the removal of energy from an object undergoing simple harmonic motion by a force opposing the motion
diffraction grating
a screen that has hundreds of slits per mm through which light can pass
Doppler effect
the change in frequency of a wave as a result of movement of the source or the observer
modulation
the reshaping of a double slit interference pattern by single slit diffraction
Rayleigh criterion
occurs when the maximum of one diffraction pattern is over the first minimum of the other
resolution
the ability to detect the two light sources as seperate
resolvance (R)
(of a diffraction grating) - the ratio between the wavelength being investigated (λ) and the smallest possible resolvable wavelength difference (∆λ)
electric field
a region of space where an object experiences a force because of its charge
electric field strength (E)
the force per unit charge experienced by a small positive test charge placed in the field
electric potential (Ve)
work done per unit charge in bringing a small positive test charge from infinity to that point
escape speed (Vesc)
the speed a body needs to escape the gravitational attraction of a planet (i.e. to reach an infinite distance away) from the surface of the planet
gravitational field
a region of space where an object experiences a force because of its mass
gravitational field strength (g)
the force per unit mass experienced by a small point test mass placed in the field
gravitational potential energy (Ep)
the work done in moving a mass from infinity to that point
gravitational potential (Vg)
the work done in taking a unit mass from infinity to that point
capacitance
ratio of charge stored to the potential difference between the plates of a capacitor
dielectric
an insulating material that can be placed between the plates of a capacitor in order to increase its capacitance
eddy currents
currents induced in the core of a transformer by the changing magnetic flux and cause energy losses by heating up the core
Faraday’s law
the magnitude of an induced emf is proportional to the rate of change of flux linkage
flux linkage
the product of the number of turns in a coil and the flux through the coil
Lenz’s law
the direction of the induced end is such that if an induced current were to flow, it would oppose the change which caused it
magnetic flux
is equal to BA cos θ, where B is magnetic field strength, A is area and θ is the angle between the field lines and the normal to the plane of area
rectification
the conversion of alternating current to direct current
rms current/voltage
the value of current or voltage is that would produce the same amount of power as the equivalent DC value
time constant
the time taken for the voltage or current to fall to 37% of its maximum value during the discharge of capacitor
becquerel
unit of activity - the number of radioactive particles being emitted per second
de Broglie wavelength
the wavelength of a matter wave
deep inelastic scattering
the scattering of high energy electrons off the quarks within the protons and neutrons of the nucleus
Heisenberg’s uncertainty principle
the simultaneous measurement of the position and momentum of a particle will always have some uncertainty
pair production
the interaction of a photon with a nucleus that produces an elementary particle and its corresponding antiparticle
photoelectric effect
the emission of electrons from a metal surface when light is shone upon it
quantum tunneling
a process whereby quantum particles can overcome potential (energy) barriers deemed impossible according to classical physics
stopping potential
the voltage at which electrons are brought to a halt as the electrical energy matches their kinetic energy
threshold frequency
lowest frequency of a light that causes electron emission from a metal’s surface
wave function
the square of the wave function gives the probability per unit volume of finding the electron at that position
work function
the minimum amount of energy needed by an electron to escape a metal’s surface
