WAVES TEST

Question 1

What are longitudinal waves?

Answer 1

Vibrations or oscillations are along the direction in ehh have the energy or wave is moving

Need a medium to move
Slinky like
Direction of movement is flat
Compressions- bunched up
Rare fraction- spaced out sections

Question 2

What are transverse waves?

Answer 2

Vibrates or oscillates at right angles to the direction in which the energy or wave is moving

Question 3

Amplitude

Answer 3

Maximum movement of particles from their resting position

Question 4

Wavelength

Answer 4

The distance between a particular point on a wave and the same point on the next wave (eg crest to crest)

Question 5

Time period

Answer 5

The period of a wave is the time for a complete cycle of the waveform

Question 6

Waves transfer energy and information without transferring matter

Answer 6

Mobile phones, satellites etc rely on waves

Question 7

Relationship between the speed, frequency and wavelength of a wave

Answer 7

Wave speed = frequency ✖️ wavelength

Question 8

Relationship between frequency and time period

Answer 8

Frequency = 1/time period

Question 9

Use the relationships in different contexts including sound waves and electromagnetic waves

Answer 9

As all waves share properties- frequency, wavelength and velocity can be used to describe all waves

Question 10

Electromagnetic spectrum

Answer 10

1 they all transfer energy
2 they are all transverse waves
3 they all travel at speed of light in a vacuum (3✖️10 to the 8 m/s
4 they can all be reflected, refracted and diffracted

Question 11

Electromagnetic spectrum, in terms of frequency

Answer 11

Increasing frequency, decreasing wavelength

Radio waves ➡️ microwaves ➡️ infra red ➡️ visible light ➡️ ultraviolet ➡️ gamma rays

Question 12

Seven colours of the visible spectrum

Answer 12

Red
Orange 
Yellow
Green
Blue
Indigo 
Violet

Red has the longest frequency and lowest frequency

Question 13

Uses of electromagnetic radiations

Answer 13

Radio waves- communicating information ➡️ radio, television, music and encoded data
➡️ because they can travel quickly
➡️ can code information
➡️ can travel long distance through buildings and walls
➡️ it is not harmful

Microwaves- commonly used in microwaves ovens, carry signals to satellites, messages sent from mobile phones are also carried by microwaves

Infrared- used in remote controls , videos and stereo systems

Visible light- main use it to see

Ultraviolet- used in security markers, kills bacteria and hardens filings

X rays- often used in x Ray machines, airport security and can be used to scan building structures for cracks

Gamma rays- sterilising medical equipment and treat cancer using radiotherapy

Question 14

Affects of electromagnetic spectrum waves

Answer 14

Microwaves➡️ internal heating
Infrared➡️ skin burns
Visible light➡️ eye damage
X rays➡️ risk of cancer and cell damage 
Gamma rays➡️ cancer and mutations

Question 15

What type of waves are light waves?

Answer 15

They are transverse waves which can be reflected and refraction
Which are omitted from luminous or non luminous objects

Question 16

Law of reflection

Answer 16

The angle of incidence equals the angle of reflection

Question 17

Properties of an image in a plane mirror

Answer 17

The image is as far behind the mirror or the object is in front
The image is the same size as the object
The image is virtual- it cannot be produced on a screen
The image is laterally inverted- the left and right side of image appear under interchanged

Question 18

How construct ray diagrams

Answer 18

Always include➡️ object, observers eye/POV, plane mirror, image and rays passing the object

Question 19

Experiments to investigate the refraction of light, using rectangular blocks, semicircular blocks and triangular prisms

Answer 19

The light bends towards the normal as it passes from low density to high density (air to glass). The light is refracted upon emerging from the glass, the light bends away from the normal as it passes for, a high to low density (glass to air)

1- place glass block on piece of paper
2- send two narrow light rays through glass
3- observe the paths of the two rays of light
4- vary the angle of incidence and measure the angle of refraction

Question 20

Relationship between refractive index, angle of incidence and angle of refraction

Answer 20

Refractive index = sin I/ sin r

(or the bigger sign over the smaller sign eg refractive index could be bigger at 60 compared to that of the sin I at 30 so then it’s 60/30 )

Question 21

What is the refractive index?

Answer 21

The ratio between the sine of the angle of incidence and the sine of the angle of refraction
- in a material, the refractive index is constant throughout

Question 22

An experiment to determine the refractive index using a glass block

Answer 22

1- place glass block on white sheet of paper
2- mark border of block with pencil
3- at one border draw a normal and draw a line to use as the incidence Ray, then put light ray along the line and draw the refracted line on other side
4- using protractor, measure the angle of incidence and the angle of refraction
5- using sin I/sin r, calculate the refractive index.

Question 23

What is total international reflection?

Answer 23

When light falls on the surface of a lighter medium from a denser medium at an angle of incidence greater than critical angle, then light does not refract?

Question 24

Conditions needed for total internal reflection

Answer 24

Light should fall in the surface of lighter medium from denser medium
Angle of incidence must be greater than the critical angle

Question 25

What are optical fibres?

Answer 25

They use the property of total international reflection, this is a very thin strand composed of two difference types of glass. The inner core is more dense than the outer one. All the fibres are narrow. Light entering the inner core always strikes the boundary of the two glasses at an angle greater than the critical angle. This technique is used to send data at light speed.

Question 26

What is the critical angle?

Answer 26

When the angle of refraction is equal to 90, the angle of incidence is called the critical angle.

Question 27

Relationship between critical angle and refractive index

Answer 27

Critical angle = 1/ refractive index

Question 28

What are type of waves are sound waves?

Answer 28

They are longitudinal waves, which can be reflected, refracted and diffracted. They reflect when they bounce back from a surface so that the angle of incidence is equal to the angle of reflection.

A REFLECTED SOUND WAVE IS CALLED AN ECHO.

sound waves refract when it changes direction when travelling across a high density medium

Sound waves are diffracted when they spread while travelling through a narrow space such as a doorway

Question 29

What is our frequency range of hearing?

Answer 29

20-20,000 Hertz

This is our audible range.

Question 30

Describe an experiment to measure the speed of sound in air

Answer 30

1- measure a large distance in an open field
2- first observer fires a starting pistol
3- second observer seeing the flash of the pistol, starts the stopwatch and then measures time until they hear sound

THIS IS CALLED THE SPEED OF SOUND