Physics definitions Flashcards
photon
- a very small quanta of discrete light energy
- can be an electromagnetic wave or particle
Absorption spectrum
- a coloured background with black lines
Emission spectrum
a black background with coloured lines
a moment
the perpendicular distance to the pivot times the force
- forces up equal forces down
- anticlockwise moments equal clockwise moments
Equilibrium
an object is in equilibrium when the resultant forces acting on a particle is zero
Couples
a pair of forces equal in magnitude and opposite in direction
Centre of mass
the point at which your mass acts through
Difference between centre of mass and centre of gravity
the gravitational field is not uniform
How to improve centre of mass
lower centre of mass
widen base of the object
kinetic energy
energy associated with anything that is moving
elastic collisions
kinetic energy and momentum is conserved
small scale
inelastic collisions
momentum is conserved
large scale
Impulse
the rate of change of momentum
current
the flow of charge per unit time
voltage
how many joules of work each coulomb of charge is capable of doing
potential difference
- the energy transfer per unit/ from electrical to other
- charge losing energy
Electromotive force
the charge gaining energy
resistivity
the resistance a metal puts up to electric current
hooke’s law
the force exerted on a spring is proportional to its compression, such that force divided by compression is equal to a constant k, which is measured in Nm
thermistor
a device that decreases its resistance as temperature increases
Young modulus
the modulus of elasticity
Brittle
something which shatters if a large stress is applied
Ductile
a material that can be easily shaped under tension
Malleable
a material that can be easily shaped under compression
Wavelength
the distance between two identical points on successive waves
amplitude
the maximum displacement of a wave
period
the time taken for one complete wave to pass a point
frequency
the number of waves that passes a fixed point per unit time
transverse waves
waves that have their displacement at 90 degrees to the direction of energy transfer
longitudinal waves
waves that have their displacement in the same direction as the energy transfer
phase difference
the amount a wave is in or out of sequence with another wave
Coherence
when two waves have a constant phase difference
refraction
when a wave travels from a fast medium to a slow medium or vice versa causing waves to slow down and speed up and turn
Interference
when two waves meet at a point, the resultant displacements the sum of individual displacements
path difference
- if the path difference is even and whole waves, the waves will arrive in phase
- if odd the waves will arrive out of phase
superconductivity
zero resistance
- occurs at low temperature
- has no resistance after a certain critical temperature
antiparticle
different charge
same mass, rest mass energy
hadrons
heavier
not fundamental
made of fundamental quarks
interacts with SNF,WNF and electrostatic if charged
leptons
lighter
fundamental
does not interact with the SNF
interacts with WNF and electrostatic force if charged
