Waves and Seismic waves

Question 1

What are the 2 types of waves

Answer 1

Longitudional and Transverse

Question 2

Amplitude

Answer 2

Maximum displacement from equilibrium

Question 3

Wavelength

Answer 3

length of one complete wave cycle - distance from peak to peak or compression to compression

Question 4

Frequency

Answer 4

Number of oscillations or cycles per second

Question 5

Time period

Answer 5

Amount of time it takes for wave to occur

Question 6

Transverse wave

Answer 6

A transverse wave is a wave that oscillates perpendicular to its propagation. A wave that vibrates at right angles to the direction of energy transfer.

Question 7

Longitudional wave

Answer 7

In longitudinal waves, the vibrations are parallel to the direction of wave travel. Longitudinal waves show areas of compression and rarefaction:

Question 8

Compression

Answer 8

compressions are regions of high pressure due to particles being close together

Question 9

Rarefraction

Answer 9

rarefactions are regions of low pressure due to particles being spread further apart

Question 10

example of longitudional wave

Answer 10

stretched spring

Question 11

example of transverse waves

Answer 11

ripple in water surface

Question 12

frequency =

measured in Hertz

Answer 12

1 / time period

Question 13

wavespeed =

Answer 13

frequency x wavelength
OR
distance / time

Question 14

What do sound waves cause in solids

Answer 14

vibrations as sound travels through solids

Question 15

what type of waves are sound waves

Answer 15

longitudional

Question 16

Waves cannot be reflected at the boundary between 2 different materials : True or False

Answer 16

False : they can

Question 17

Waves can be absorved or transmitted at the boundary between 2 different materials : True or False

Answer 17

True

Question 18

what causes sound

Answer 18

vibrations

Question 19

Mechanical Waves

Answer 19

needs a medium to pass through

Question 20

Medium

Answer 20

A general name for a material that a wave is passing through.

Question 21

reflection

Answer 21

This occurs when a wave travelling in one medium strikes the surface of a different medium and changes direction so that it returns back into the medium in which it was originally travelling in.

Question 22

Transmission

Answer 22

Transmission is the movement of a wave through a medium or from one medium into another.

Question 23

Absorption

Answer 23

Absorption is when the energy being transferred by a wave is taken into an energy store of a material.

Question 24

Can sound waves can travel through solids causing vibrations in the solid?

Answer 24

yes

Question 25

how do we feel the sensation of sound

Answer 25

Sound waves make ear drum vibrate, causing sound. Conversion of sound waves to vibrations of solids works over a limited frequency range.

Question 26

frequency range of normal Human hearing

Answer 26

20 Hz to 20kHz

Question 27

Ultrasound

Answer 27

Waves with a frequency higher than the upper hearing limit for humans

Question 28

what happens when ultrasound waves meet the boundary of 2 different media

Answer 28

they are partially reflected

Question 29

How can ultrasound waves be used for medical and industrial imagery.

Answer 29

Time taken for reflections to reach detector can be used to determine the distance to the boundary when the speed of the wave is known.

Question 30

Speed of sound in air?

Answer 30

330 m/s

Question 31

what is a reflected sound called

Answer 31

echo

Question 32

are hard or soft surfaces best at reflecting sound

Answer 32

hard surfaces

Question 33

Focus

Answer 33

The focus is the place inside Earth’s crust where an earthquake originates

Question 34

Epicentre

Answer 34

The point on the Earth’s surface directly above the focus is the epicentre

Question 35

what two waves do earthquakes produce

Answer 35

Shock waves and seismic waves

Question 36

two types of seismic waves

Answer 36

P waves and S waves

Question 37

What are P waves

Answer 37

longitudional seismic waves, travels fastest and through solids, liquids or gases.

Question 38

why do P waves travel fastest in solids

Answer 38

p-wave velocity increases with depth and increases with increasing rigidity of a material.

Question 39

S waves

Answer 39

transverse seismic waves, can only travel through solid. Slower than P waves

Question 40

Law of reflection

Answer 40

angle of incidence = angle of reflection

Question 41

Angle of incidence

Answer 41

The angle of incidence is the angle between the direction of motion of the wave and a line drawn perpendicular to the reflecting boundary.

Question 42

how are angle of incidence and reflection measured

Answer 42

The angles of incidence and reflection are measured between the light ray and the normal - an imaginary line at 90° to the surface.

Question 43

Specular reflection

Answer 43

Reflection from a smooth, flat surface is called specular reflection. This is the type of reflection that happens with a flat mirror.

Question 44

Diffuse reflection

Answer 44

If a surface is rough, diffuse reflection happens. Instead of forming an image, the reflected light is scattered in all directions. This may cause a distorted image of the object, as occurs with rippling water, or no image at all. Each individual reflection still obeys the law of reflection, but the different parts of the rough surface are at different angles.