Waves

1) What is a Wave ?
A wave is a vibration that transports energy from one place to another without transporting mass.
All objects send out invisible waves called radiation to their surroundings.
The matter does not move.

2) What are the three different ways of categorising waves in terms of the direction of particle movement ?
Longitudinal - (sound)
Transverse - (electromagnetic, inc light) and stretched springs
Surface -

3) What is a Longitudinal Wave ?
When the direction of the vibration is in the same as that of the wave
The particles oscillate parallel to the direction of the energy.
The particles vibrate (or oscillate) and pass the energy onto the next particle.
Needs a medium to travel through.

4) What is a Transverse Wave ?
When the direction of the vibration is perpendicular to that of the wave.
The particles oscillate perpendicular to the direction of the energy.
Does not need a medium to travel through.

5) What is the Frequency of a wave ?
The number of waves produced in one second, measured in hertz.

6) What is the Period of a wave ?
The time it takes for a full wave to pass a given point, measure in seconds.
This is 1 divided by frequency.

7) What is the Wavelength of a wave ?
The distance between two corresponding points on a wave, in metres.

8) What is the Amplitude of a wave ?
The distance from the middle to either the top or bottom.
The maximum amount of vibration, usually measured in metres

9) What is the difference between the Crest and the Trough ?
Crest (or Peak) - the top of a wave.
Trough - the bottom of a wave.

10) What is the relationship between Frequency and Wavelength ?
The higher the frequency, the shorter the wavelength
The lower the frequency, the longer the wavelength
Frequency and wavelength are inversely proportional to each other.

11) How do you calculate Wave Speed ?
Speed = Frequency x Wavelength

12) What are the units for Wave Speed ?
Metres per Second

13) Does the speed of a wave have anything to do with the Amplitude ?
No. The size of the wave does not affect the speed.

14) What is Transmission ?
This is where the waves travel through a medium rather than being absorbed or reflected

15) What is Absorption ?
When energy is transferred from sound (or other types of waves) to a material

16) What is Displacement ?
Calculate the speed of a wave that has a wavelength of 42 cm and a frequency of 11 hertz.
speed = frequency x wavelength

17) What is a Mechanical Wave ?
This is a wave that is an oscillation of matter and requires vibration in a solid, liquid or gas.
These can travel through air and solid materials (not through a vacuum)
Examples include - sound, water, stretched string

Sound Waves

18) What is Sound ?
These are longitudinal waves that need a medium to travel through.
It is impossible for sound to travel through a vacuum because there are no air molecules to vibrate.

19) What is the speed of Sound ?
The distance sound travel in one second (330 m/s)

20) What is a Pressure Wave ?
It is a wave that has a repeating pattern of high pressure regions and low pressure regions (for example sound)

21) What is an Oscilloscope ?
A device that is able to view patterns of sound waves that have been turned into electrical signals.

22) How does Frequency affect Sound ?

23) What is the Pitch of a wave ?

24) How are Pitch and Frequency related ?
A low pitch sound has a low frequency.
A high pitch sound has a high frequency.

25) How does a Loudspeaker work ?
It uses an electromagnet to make sound from a varying potential difference.
It turns an electrical signal into a pressure wave of sound.
The changing P.d. causes changes in air pressure.

26) How does a Microphone work ?
sound can be detected with a microphone.
It turns any pressure waves that hit is into an electrical signal (or potential difference)

27) What do you need to do to a sound wave to make it louder ?
Increase the amplitude.

28) What is an Echo ?
Reflection of sound waves from a surface back to the listener

29) Can you give the names of some of the bones in the inner ear ?
hammer, anvil, stirrup

30) Can you give the names of some of the bones in the outer ear ?
pinna, auditory canal, eardrum

31) What is Ultrasound ?
Sound at a frequency greater than 20,000 Hz
this is beyond the range of human hearing

32) What frequency can humans hear ?
Between 20-20,000 Hz

33) What are Decibels ?
The unit used to measure the loudness of sound.

Visible Light

34) What is Visible Light ?
These are transverse waves that do not need a medium to travel through.
They have a frequency that human eyes can detect.

35) What is the speed of Light ?
The distance light travels in one second (300 million m/s)

36) What is Ultraviolet light ?
These are light waves that have a higher frequency than the light that human eyes can detect.

37) What are the 3 Primary colours ?
Red, Blue, Green
All colours can be broken down into different combinations of the three primary colors.

38) What is a Secondary colour ?
It is a colour obtained by mixing two primary colours together.
R + B = Magenta
R + G = Yellow
B + G = Cyan

39) What colour would these objects be ?
blue object in blue light (blue)
blue object in red light (black)
blue object in green light (black)
yellow object in red light (red)
yellow object in blue light (black)

40) What is Angle of Incidence ?
The angle between the normal and incident ray

41) What is Angle of Reflection ?
The angle between the normal and the reflected ray

42) What is the Law of Reflection ?
The angle of incidence is equal to the angle of reflection

43) What is a Lens ?
A device made up shaped glass that focusses light rays from objects to form an image

44) What is the difference between a Concave Lens and a Convex Lens ?
Concave - A lens that is thinner in the middle and that spreads out light rays
Convex - A lens that is thicker in the middle and that bends light rays towards each other

45) What is a Shadow ?
A shadow is formed when light travelling in straight lines from a light source is blocked by an opaque object.

46) What is a Mirror ?
Is an object that reflects light at the same angle that it hits.

47) What is Converging ?
Bringing rays of light together

48) What is Dispersion ?
Splitting up of a ray of light of mixed wavelengths into separate components by using refraction

49) What is Diverging ?
The type of lens that spreads light out and forms a virtual image

50) What is the Focal Point ?
The point at which light rays refracted by a convex lens cross over

51) What is an Incident Ray ?
The incoming ray from a source of light

52) What is an Reflected Ray ?
Light rays that are bounced off a surface.

53) What is Opaque ?
A material that does not allow light to pass through it

54) What is a Non-Luminous object ?
An object that produces no light.

55) What is the optic nerve ?
A pair of sensory nerves that run from each eye to the brain.

56) What are the difference parts of the eye called ?
Pupil - the hole in front of your eye called where light goes in.
Iris - the coloured part of your eye called.
Retina - the back of the eye where the image is formed.
Cornea - the transparent layer at the front that refracts light.

57) What is Refraction ?
This is when light bends when it crosses a boundary between two different substances.

58) What is a Spectrum ?
A band of light produced when light is spread out by a prism.

59) What is a Translucent material ?
A material that allows some light to pass through it

60) What is a Transparent material ?
A material that allows all light to pass through it.