Exam III Vocabulary Flashcards
wavelength
distance from the top of one crest to the top of the next crest, the smallest repeating unit of a wave. Represented by the symbol: λ (lambda)
wave speed
describes how fast a disturbance moves through a medium
wave speed = (frequency)(wavelength)
transverse wave
the particles of the medium vibrate perpendicular to the direction of the motion of the wave/energy transfer
ie: radio waves, lightwaves
longitudinal wave
the particles of the medium vibrate in the same direction as the motion of the wave/energy transfer
ie: sound waves in a solid, liquid or gas
standing wave
when waves that travel from one end to another encounter a fixed end, the waves get reflected back. standing waves are composed of a node (point of zero displacement) and an antinode (point of max displacement)
ie: stringed instruments
frequency
number of cycles per second. specifies the “to” and “fro” vibrations in a given time
hertz
the unit for frequency
NOTE: frequency of 1 Hz is a vibration that occurs once each second
doppler effect
increase in light frequency when a light source approaches you / decrease in light frequency when a light source moves away from you
ie: also applies to sound.
ohm’s law
the relationship between voltage, current, and resistance in a circuit
ie: current (I) = voltage/resistance
electric power
the rate at which energy is transferred in a circuit. measured in watts
ie: electric power = (current)(voltage)
series circuit
forms a single pathway for electron flow between the terminals of the battery, generator, or wall outlet
parallel circuit
forms branches, each of which is a separate path for the flow of electrons
electrical resistance
ability of a conductor to resist the flow of electrons through it. measured in ohms
potential difference
the difference in electric potential between two points, measured in volts.
direct current
(dc) flows in only one direction. electrons move from the negative terminal to the positive terminal
alternating current
(ac) electrons in the circuit are moved first in one direction and then in the opposite direction, alternating “to” and “fro” about fixed positions
accomplished by alternating the polarity of voltage at the generator or other voltage source
electromagnetic induction
the creation of voltage when a magnetic field changes with time. if the magnetic field within a closed loop changes in any way, a voltage is induced in the loops
faradays law
the induced voltage in a coil is proportional to the product of its number of loops, the cross-sectional area of each loop, and the rate at which the magnetic field changes within those loops
electromagnetic wave
an energy-carrying wave emitted by a vibrating charge that is composed of oscillating electric and magnetic fields that regenerate one another
NOTE: electromagnetic waves travel at the speed of light, 3x10^8 m/s
transformer
a device for transferring electric power from one coil of wire to another, by means of electromagnetic induction, for the purpose of transforming one value of voltage to another
generator
an electromagnetic induction device that produces electric current by rotating a coil within a stationary magnetic field.
NOTE: a generator converts mechanical energy to electric energy