Exam III Vocabulary

Question 1

wavelength

Answer 1

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)

Question 2

wave speed

Answer 2

describes how fast a disturbance moves through a medium

wave speed = (frequency)(wavelength)

Question 3

transverse wave

Answer 3

the particles of the medium vibrate perpendicular to the direction of the motion of the wave/energy transfer

ie: radio waves, lightwaves

Question 4

longitudinal wave

Answer 4

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

Question 5

standing wave

Answer 5

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

Question 6

frequency

Answer 6

number of cycles per second. specifies the “to” and “fro” vibrations in a given time

Question 7

hertz

Answer 7

the unit for frequency

NOTE: frequency of 1 Hz is a vibration that occurs once each second

Question 8

doppler effect

Answer 8

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.

Question 9

ohm’s law

Answer 9

the relationship between voltage, current, and resistance in a circuit

ie: current (I) = voltage/resistance

Question 10

electric power

Answer 10

the rate at which energy is transferred in a circuit. measured in watts

ie: electric power = (current)(voltage)

Question 11

series circuit

Answer 11

forms a single pathway for electron flow between the terminals of the battery, generator, or wall outlet

Question 12

parallel circuit

Answer 12

forms branches, each of which is a separate path for the flow of electrons

Question 13

electrical resistance

Answer 13

ability of a conductor to resist the flow of electrons through it. measured in ohms

Question 14

potential difference

Answer 14

the difference in electric potential between two points, measured in volts.

Question 15

direct current

Answer 15

(dc) flows in only one direction. electrons move from the negative terminal to the positive terminal

Question 16

alternating current

Answer 16

(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

Question 17

electromagnetic induction

Answer 17

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

Question 18

faradays law

Answer 18

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

Question 19

electromagnetic wave

Answer 19

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

Question 20

transformer

Answer 20

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

Question 21

generator

Answer 21

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