ch4

Question 0

The lines that are used to show the path of light are called what?

Answer 0

Rays

Question 1

At what speed does light travel through space?

Answer 1

299.972458km/s

Question 2

What is a stream of light rays called?

Answer 2

A beam

Question 3

The light may ‘bounce off’ the surface of the substances. What is this called and what does it allow you to see?

Answer 3

This is called reflection, and is what allows you to see non-luminous objects

Question 4

Finish the sentence. Luminous objects are those that can…

Answer 4

Emit light

Question 5

What are luminous objects?

Answer 5

Luminous objects are those that can emit light

Question 6

List some examples of luminous objects.

Answer 6

The sun and the flame of a burning match are examples of luminous objects.

Question 7

Light can also be reflected from the particles within substances
This is called what and why?

Answer 7

This is called scattering because the light bounces off in so many different directions.

Question 8

What can light be scattered by?

Answer 8

Light is scattered by particles such as fog, dust and smoke in the atmosphere.

Question 9

The light may travel through the substance. Some light is always reflected when light crosses a boundary between two substances
If most of the light travels through the substance, the surface is called what and why?

Answer 9

Transparent. Because enough light gets through for you to be able to see objects clearly on the other side.

Question 10

True or false? Light is never reflected when light crosses a boundary between two substances.
(Justify your answer)

Answer 10

False. There is always some light that is reflected when light crosses a boundary between two substances.

Question 11

Some materials let just enough light through to enable you to detect objects on the other side, but scatter so much light that you cannot see them clearly. Such materials are said to be what?

Answer 11

Translucent.

Question 12

What is an example of a translucent object?

Answer 12

The ‘frosty’ glass used in some shower screens is an example.

Question 13

What materials are said to be translucent?

Answer 13

Materials that let just enough light through to enable you to detect objects on the other side, but scatter so much light that you cannot see them clearly.

Question 14

The light may be absorbed by the substance, transferring its energy to the particles in the substance. Substances which do what are said to be what?

Answer 14

Substances which absorb or reflect all the light striking them are said to be opaque.

Question 15

What objects are said to be opaque?

Answer 15

The light may be absorbed by the substance, transferring its energy to the particles in the substance. Substances which absorb or reflect all the light striking them are said to be opaque.

Question 16

When light travels from one substance to substance that is transparent or translucent, what can happen?

Answer 16

It can slow down or speed up.

Question 17

When light travels from one substance to substance that is transparent or translucent, it can slow down or speed up. This change in speed as light travels from one substance to another is called what?

Answer 17

refraction

Question 18

What can refraction cause light to do?

Answer 18

Refraction causes light to bend, unless it crosses at right angles to the boundary between the substances.

Question 19

The best way to describe which way the light bends is to draw a line at right angles to the boundary. What is this line called?

Answer 19

The normal

Question 20

What is a biconcave lens?

Answer 20

It is curved inwards, like a cave, on both sides. A beam of light travelling through a biconcave lens spreads out (diverges).

Question 21

What is a biconvex lens?

Answer 21

A magnifying glass is an example of a converging lens
It is biconvex in shape. A beam of light travelling through a biconvex lens ‘closes in’ (converges) towards a point called the focus.

Question 22

What is the distance between the focus and the centre of the lens called?

Answer 22

The focal length

Question 23

The vibration creates regions of space in which the air particles are bunched together are called what?

Answer 23

Compressions

Question 24

The vibration creates regions in which they are more spread out, are called what?

Answer 24

rarefactions

Question 25

What is a sound wave?

Answer 25

A sound wave is the movement of alternating compressions and rarefactions.

Question 26

How is sound produced?

Answer 26

Sound is produced when something vibrates, which means to move back and fourth very quickly.

Question 27

Name some sounds and their vibrating source.

Answer 27

Speech- Flaps of skin, called vocal chords.
Drum- Drum skin.
Saxophone- Reed inside the mouthpiece.
Car stereo system- Speaker cone.
A bell ringing- Metal casing of the bell (when struck)
Piano- String inside the piano

Question 28

In what way do sound waves travel?

Answer 28

Sound waves travel away from the source of a sound, in the same way that ripples out of water move outwards when a stone is dropped into a pond.

Question 29

Because the sound wave relies upon particles that vibrate for it to be transmitted, what must be present for a sound to be produced?

Answer 29

A solid (such as a railway track), a liquid (such as water in a swimming pool) or a gas (such as air) is needed for a sound to be produced

Question 30

A wave carries energy from one point to another. This can happen in a couple of ways. The energy carried by waves at the beach moves horizontally, but the particles making up the wave actually move in a vertical direction. This type of wave is called…

Answer 30

a transverse wave

Question 31

What determines the speed a sound wave will travel through a medium?

Answer 31

The more closely packed the particles in a medium (a ‘medium’ is the surrounding environment), the faster a sound wave will travel through it.

Question 32

The more closely packed the particles in a medium (a ‘medium’ is the surrounding environment), the faster a sound wave will travel through it. As a result…

Answer 32

Sound travels faster through solids than through liquids, and faster through liquids than gases.

Question 33

True or false? Sound travels faster in warmer air than in cooler air. Justify your answer.

Answer 33

True, because the particles in warmer air move with greater kinetic energy.

Question 34

Describe the pinna.

Answer 34

This is the out ear. It funnels sound into the ear canal.

Question 35

Describe the ear drum.

Answer 35

(Separates the outer ear and middle ear).
This thin flap of skin stretches tight across the inside of the ear like the skin on a drum. Sound reaching the ear drum makes it vibrate.

Question 36

Describe the ossicles.

Answer 36

Vibrations of the eardrum pass onto the ossicles, three tiny bones, called the hammer, anvil and stirrup. These bones magnify the vibrations.

Question 37

Describe the oval window.

Answer 37

Separates the middle and inner ear. Vibrations from the stirrup are transmitted to this thin layer of tissue, and continue through to the cochlear.

Question 38

Describe the semicircular canals.

Answer 38

These are filled with fluid and give us our sense of balance. They don’t play a role in our hearing but may be affected if we have a cold or ear problem.

Question 39

Describe the auditory nerve.

Answer 39

Electrical impulses travel along this nerve to the brain, which interprets them as sound.

Question 40

Describe the cochlear.

Answer 40

This spiral shaped tube is filled with fluid. Vibrations cause this fluid to move, and are detected by millions of tiny hairs lining the surface of the cochlear. Receptors attached to these hair convert their movement into electrical impulses.

Question 41

Describe the eustachian tube

Answer 41

Joins the middle ear to the nose and throat. Air moves into, or out from the middle ear through this tube to balance the air pressure on the other side of the ear drum.

Question 42

Over one million Australians have a hearing disability, ranging from mild hearing loss to complete deafness.
These problems can be because:

Answer 42

The ear canal is blocked with wax, preventing the passage of sound waves
The middle ear is filled with fluid
The eardrum has been ruptured by an extremely loud noise or as the result of infection
Sensory cells of the ear have been damaged by loud noise
A defect in the auditory nerve or the tiny hairs of the cochlea prevents sound impulses being transmitted correctly to the brain