PHYSICS: WAVES

Question 1

Motion

Answer 1

Change in position relative to frame of reference

Question 2

Wave

Answer 2

-rhythmic disturbance that travels through matter or space
-wave motion is a means of transferring energy
-the two basic types of waves are longitudinal and transverse waves

Question 3

Transverse wave

Answer 3

-wave in which matter vibrates at right angles to the direction in which the wave travels
-ex. water waves approximate a transverse wave, and light and heat appear to be transmitted by transverse waves

Question 4

Longitudinal wave

Answer 4

-wave in which matter vibrates back-and-forth along the path that the wave travels
-sounds, for example, are transmitted by longitudinal waves

Question 5

Periodic motion

Answer 5

Motion that repeats itself over and over again, such as the motion of a pendulum

Question 6

Periodic wave

Answer 6

-motion that repeats itself at regular intervals and that transfers energy but not mass
-the time it takes for the motion to repeat itself is measured in seconds and is called the period
-a cycle is equal to one complete repetition of a periodic event
-the frequency (f) of a wave tells us how often a cycle repeats itself in a specific time unit
-frequency is often measured in hertz (Hz) which is equivalent to cycles per second

Question 7

Amplitude

Answer 7

-refers to the maximum distance a wave rises or falls as it travels, and it is related to the energy that the wave carries
-ex. amplitude relates to brightness with light waves and to loudness with sound waves
-the louder the sound or the brighter the light is, the higher the amplitude is
-the crest of a transverse wave is the maximum upward displacement
-the trough is the maximum downward displacement

Question 8

the wavelength of a transverse wave

Answer 8

-the distance between two successive crests

Question 9

wave speed

Answer 9

-the frequency of the wave times the wavelength
Frequency x wavelength

Question 10

Diffraction

Answer 10

-bending of waves around an obstacle
-when two waves meet, they combine to make the new wave
-Light bends when it passes around an edge or through a slit

Question 11

Interference

Answer 11

how the waves interact with each other when they go through the same portion of a medium at the same time

Question 12

Resonance

Answer 12

Between two systems occurs when the vibration of one system results in the vibration of the other system at the same frequency

Question 13

Photons

Answer 13

-tiny packets of energy
-light waves are made up of streams of photons
-the amount of energy in the photons determines the kind of light wave produce

Question 14

Electromagnetic waves

Answer 14

Light waves are called electromagnetic waves because the moving photons generate electric and magnetic fields

Question 15

Electromagnetic spectrum

Answer 15

-the complete spectrum of light, arranged in order of their wavelengths
-visible light, only a small part of the spectrum, is the portion that is visible to the human eye
-the electromagnetic spectrum consists of:
radio waves
infrared waves
visible light
ultraviolet light
x-rays
gamma rays
-gamma rays: highest energy photons, shortest wavelengths
-the photons of visible light contain a moderate amount of energy, while x-rays are made up of high energy photons and radio waves, which contain low energy photons
-gamma rays have the highest energy photons and the shortest wavelength of all the electromagnetic waves

Question 16

Sound waves

Answer 16

-are longitudinal waves
-they vibrate in the direction of their motion

Question 17

Pitch

Answer 17

-the pitch of a sound wave has to do with the frequency
-high frequency sound waves have a high pitch, and low frequency waves have a low pitch
-the loudness of a sound wave is determined by its amplitude

Question 18

Doppler effect

Answer 18

-occurs whenever there is relative motion between the source of waves and the observer
-ex. the pitch of a siren gets higher as an ambulance approaches you and lower as it drives away
-the siren has not changed its frequency, but the motion of the ambulance toward you increases the frequency of the sound waves you hear
-as the siren moves away, the frequency you hear is less than the source frequency, and the pitch is lower

Question 19

Reflection

Answer 19

-when a light wave bounces off a surface that does not absorb its energy, it is reflected
-the type of surface that light strikes determines the kind of reflection
-because a mirror is a smooth, flat surface, the reflected rays are not scattered and the image reflected is clearly defined

Question 20

Refraction

Answer 20

-the bending of light rays as they pass from one medium to another
-because light moves at different speeds through different mediums, as light passes from one medium to another, it either speeds up or slows down

Question 21

Dispersion

Answer 21

-a prism is a piece of glass that separates light into its component colors, this phenomenon is called dispersion
-the phenomenon of splitting of a beam of white light into its seven constituent colours when passed through a transparent medium such as a prism

Question 22

Lens

Answer 22

-Any transparent material that refracts light
-when parallel rays of light pass through a lens, they refracted so that they either come together or spread out

Question 23

Convex lens

Answer 23

-is thicker in the center than it is at the edges
-when parallel rays of light pass through a convex lens, they converge, or bend toward the center

Question 24

Focal point

Answer 24

Point at which the light rays meet

Question 25

Concave lens

Answer 25

-thicker at the edges than it is in the middle
-when light rays pass through a concave lens, they diverge because they are bent toward the edges, or the thickest part, of the lens
-images of an object produced by concave lenses are smaller than the object