7Th Grade Science Chapter 2

Front 1

wave

Back 1

a disturbance that transfers energy from place to place

Front 2

energy

Back 2

the ability to work

Front 3

medium

Back 3

the material through which a wave travels

Front 4

vibration

Back 4

a repeated back- and - forth or up-and-down motion

Front 5

crest

Back 5

the high point of a wave

Front 6

amplitude

Back 6

the maximum distance that the particles of the medium carrying the wave move away from their rest positions

Front 7

trough

Back 7

the low point of a wave

Front 8

wavelength

Back 8

the distance between two corresponding parts of a wave

Front 9

frequency

Back 9

the number of complete waves that pass a given point in a certain amount of time

Front 10

electromagnetic wave

Back 10

transfers electrical and magnetic energy

Front 11

electromagnetic radiation

Back 11

the energy that is transfered through space by electromagnetic waves

Front 12

electromagnetic spectrum

Back 12

the complete range of electromagnetic waves placed in order of increasing frequency

Front 13

visible light

Back 13

electromagnetic waves that you can see

Front 14

transparent

Back 14

material transmits most of the light that it strikes

Front 15

translucent

Back 15

material scatters light as it passes through

Front 16

opaque

Back 16

material reflects or absorbs all of the light that strikes it

Front 17

primary colors

Back 17

three colors that can combine to make any other color

Front 18

secondary color

Back 18

two primary colors combine in equal amounts

Front 19

complementary colors

Back 19

any two colors that combine to form white light

Front 20

pigments

Back 20

colored substances that are used to color other materials

Front 21

reflection

Back 21

when an object or wave bounces back off a surface through which it cannot pass

Front 22

law of reflection

Back 22

the rule that the angle of reflection equals the angel of incidence

Front 23

plane mirror

Back 23

is a flat sheet of glass that has a smooth, silver- colored coating on one side

Front 24

image

Back 24

a copy of an object formed by reflected or refracted rays of light

Front 25

virtual image

Back 25

an upright image that forms where light seems to come from

Front 26

concave mirror

Back 26

a mirror with a surface that curves inward like the inside of a bowl

Front 27

optical axis

Back 27

an imaginary line that divides a mirror in half

Front 28

focal point

Back 28

the point at which rays parallel to the optical axis meet or converge

Front 29

real image

Back 29

forms when rays actually meet

Front 30

convex mirror

Back 30

a mirror with a surface that curves out

Front 31

refraction

Back 31

bending of light waves due to a change in speed

Front 32

lens

Back 32

a curved piece of glass or other transparent material that refracts light

Front 33

convex lens

Back 33

a magnifying glass that is thicker in the center than at the edges

Front 34

cornea

Back 34

the transparent front surface of the eye that light enters through

Front 35

pupil

Back 35

an opening through which light enters the inside of the eye

Front 36

iris

Back 36

a ring of muscle that contracts and expands to change the size of the pupil

Front 37

retina

Back 37

a layer of cells that lines the inside of the eyeball

Front 38

rods

Back 38

something that contains the pigment that responds to small amounts of light

Front 39

cones

Back 39

something that responds to color

Front 40

nearsighted

Back 40

a person that can see nearby things clearly, but objects at a distance are blurred

Front 41

farsighted

Back 41

a person that can see distant objects clearly, but nearby objects appear blurry

Front 42

camera

Back 42

something that uses one or more lenses to focus light, and film to recored an image

Front 43

telescope

Back 43

something that forms enlarged images of distant objects

Front 44

refracting telescope

Back 44

something that consists of two convex lenses, one at each end of a tube

Front 45

objective

Back 45

something that gathers the light coming from an object and focuses the rays to form a real image

Front 46

eyepiece

Back 46

something that magnifies the image so you can see it clearly

Front 47

reflecting telescope

Back 47

something that uses a large concave mirror to gather light

Front 48

microscope

Back 48

something that is an optical tool that makes small objects look larger

Front 49

electron microscope

Back 49

a microscope that uses a beam of electrons to produce a magnified image