Waves Test

Question 1

How is sound produced

Answer 1

Vibrations

Question 2

Describe the nature of longitudinal waves

Answer 2

Longitudinal waves vibrate parallel to the flow of energy

Question 3

What is the approximate range of hearing for the human ear

Answer 3

20Hz-20,000Hz/20kHz

Question 4

What is meant by ultra sound

Answer 4

Ultra sound is sound waves with frequencies greater then human hearings capacity (20kHz)

Question 5

What is needed to transmit sound waves

Answer 5

A connecting medium

Question 6

Describe an experiment to determine the speed of sound in air

Answer 6

• Man with gun stands x number of meters away (far)
• Start timer when smoke is seen, stop when sound is heard
• divide distance (x) by time on stop watch
• repeat and avg for better test

Question 7

How do amplitude and frequency affect the sound heard by sound waves

Answer 7

• The higher the frequency the higher the pitch of the note

- The higher the amplitude the louder the note

Question 8

Describe how reflection of sound may produce an echo

Answer 8

Sound waves can reflect off of smooth, hard surfaces. The only thing that changes is the direction meaning the same sound can be heard twice

Question 9

Describe a compression and a rarefaction

Answer 9

compressions are regions of high pressure due to particles being close together. rarefactions are regions of low pressure due to particles being spread further apart.

Question 10

State estimate values for the speed of sound in solids, liquids and gasses

Answer 10

Solids - 4,000m/s
Liquids - 1,450m/s
Gas - 330m/s

Question 11

Waves transfer ______ without transferring ______

Answer 11

Waves transfer energy without transferring matter

Question 12

Describe what is meant by wave motion

Answer 12

deviations from a state of rest or equilibrium—from place to place in a regular and organized way. As shown in ripple tanks, and by shaking a rope or a spring.

Question 13

What is meant by the term wave front?

Answer 13

An imaginary surface representing corresponding points of a wave that vibrate in unison

Question 14

Give the meaning of: speed, frequency, wavelength and amplitude

Answer 14

Speed - the distance traveled over a time
Frequency - the number of complete waves passing a set point per second
Wave length - the distance between a point on one wave, and the same point on the next wave
Amplitude - the maximum displacement of a wave from its resting point (point of equilibrium)

Question 15

Distinguish between transverse and longitudinal waves and give examples of each

Answer 15

• Transverse waves vibrate perpendicular to the flow of energy, longitudinal waves vibrate parallel to the flow of energy
• sound waves are longitudinal waves, electromagnetic waves (radio waves, micro waves…) are transverse waves

Question 16

How do waves undergo reflection

Answer 16

Waves, when hitting a smooth, hard surface, reflect (change directions) the only thing that changes is the direction

Question 17

How do waves undergo refraction

Answer 17

When changing from their current medium to one with a different density the speed of the wave changes changing its direction , the only thing that changes is the direction

Question 18

How do waves undergo diffraction

Answer 18

When waves meet a gap in a barrier they spread out to some extent. Gaps larger then the wavelength create little spreading, Gap’s similar to the wavelength cause a lot of spreading.

Question 19

What is the wave equation

Answer 19

V=f x lambda

Wave speed = wave frequency x wavelength

Question 20

State the waves in the electromagnetic spectrum in order of wavelength

Answer 20

From largest to smallest, radio waves, micro waves, infra-red, visible light, ultra-violet, x-rays, gamma rays

Question 21

All electromagnetic waves travel at the same high speed in _______, this is the speed of _____

Answer 21

All electromagnetic waves travel at the same high speed in vacuums, this is the speed of light

Question 22

Describe uses of radio waves

Answer 22

Radio and television communication

Question 23

Describe uses of micro waves

Answer 23

Satellite television and telephones

Question 24

Describe uses for infra-red waves

Answer 24

Electrical appliances, remote controls, intruder alarms

Question 25

Describe uses of X-rays

Answer 25

Medicine and security

Question 26

What are some safety issues regarding micro waves and x-rays

Answer 26

Prolonged exposure to either microwaves or x-rays can produce serious long term health risks

Question 27

Describe the formation of an image by a plain mirror and describe its characteristics

Answer 27

- Images are formed on a plain by reflecting the light waves hitting it - Optical images are virtual, upright, left-right reversed, the same distance from the mirror as the object and the same size as the object

Question 28

The angle of _________ = the angle of __________

Answer 28

The angle of incidence = the angle of reflection

Question 29

The image in a plain mirror is _______

Answer 29

The image in a plain mirror is virtual

Question 30

Practice constructions

Answer 30

Do it 😈🥵😡

Question 31

Describe an experimental demonstration for the refraction of light

Answer 31

Perspex block, laser pointer, shined in one side, refracted out the other, measure angles

Question 32

Describe the passage of light through a parallel sided, transparent material

Answer 32

When light passes from one medium with a certain density to another with a different density it bends, this is called refraction.

Question 33

What is the critical angle

Answer 33

The critical angle is the angle of incidence, beyond which, rays of light passing through a denser medium to the surface of a less dense, are totally reflected

Question 34

What is the refractive index

Answer 34

The refractive index is the extent to which light is refracted when it enters a medium

Question 35

Sin i/sin r = ?

Answer 35

n/refractive index

Question 36

1/sin c (critical angle) = ?

Answer 36

n/the refractive index

Question 37

Give some uses of optical fibres in medicine and technology

Answer 37

- optical fibres are used in endoscopes to help doctors see inside patients - optical fibres transfer lots of information as pulses of light, to be converted into binary

Question 38

Describe the dispersion of light from a glass prism

Answer 38

Upon passage through the prism, the white light is separated into its component colors - red, orange, yellow, green, blue and violet

Question 39

Light of a single frequency is described as _____________

Answer 39

Light of a single frequency is described as monochromatic

Question 40

Describe the action of a converging lens of a wave of light

Answer 40

A converging lens causes the light rays that are travelling parallel to its principal axis to refract and cross the principal axis at a fixed point called the focal point

Question 41

What do “principal focus” and “focal point” mean

Answer 41

- The principal focus is the point from which the waves appear to spread out - the focal point is the point at which all the waves converge

Question 42

Describe the use of a single lens as a magnifying lens

Answer 42

A magnifying glass is a convex lens used to make an object appear much larger than it actually is

Question 43

What is meant by a virtual and real image

Answer 43

- A virtual image is an image that is not actually where it is seen to be, it comes from behind the lens - A real image is an image that is actually where it is seen to be, the light rays pass through it