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Pearson Science • Year 9 Sem 2 > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

Define heat (4.1)

A

A form of energy that can be transferred through solids, liquids and gases.

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2
Q

Explain why you shouldn’t touch a water bottle during winter if you’re cold. (4.1)

A

Because heat travels from an area of high to low concentration. So therefore, the heat left on your hands (high concentration) would transfer to the bottle (low concentration).

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3
Q

Describe the particle model.

A

Solids: they are tightly compacted together and vibrate slowly, allowing it to hold its shape.
Liquids: compacted tightly but have more space between them, allowing them to move over each other and flow. Vibrate quicker than solid, holds shape of container.
Gases: Not bound together and travel in straight lines until they bump into each other. Particles spread out and take shape of container.

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4
Q

Explain what happens when you heat a substance.

A

When you heat a substance, the energy from the source transfers to the particles giving them kinetic energy so they begin to vibrate, and this turns into heat energy.

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5
Q

Why does expansion and contraction occur?

A

Expansion occurs when a substance is heated. They eventually gain so much energy that they break out of their state and become a liquid or gas. This explains why an ice cube melts into water and then evaporates into gas, vice versa for contraction.

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6
Q

Define temperature

A

Measure of the average kinetic energy of the particles of a substance.

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7
Q

What is ‘absolute zero’?

A

The point of temperature when there is no more heat and energy, the particles of the substance barely move at all. (-273 degrees celcius, 0 Kelvin)

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8
Q

How does a thermometer work?

A

Contains mixture of alcohol/mercury which expands/contracts and we can read the temperature based on the scale that corresponds. (mercury isn’t used much anymore due to health hazards - if it breaks it will evaporatre, intoxicating the air)

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9
Q

The ____ the temperature difference, the ____ the flow of heat.

A

When the temperature difference is greater, heat transfers faster. This explains why warm water freezes faster than cold water.

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10
Q

Define conduction and provide an example.

A

The method of heat transferring between two substances in contact in which heat is transferred by vibration of particles. Eg. Holding an ice block on your hands. Heat from hands (high temp.) transfer to ice (low temp.) Your hand becomes cold and the ice melts.

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11
Q

Contrast conductors and insulators.

A

Conductors are substances that transfer heat easily. Eg. Metal. Insulators are substances that are poor conductors. Eg. Gases can still hold heat but poorly conduct it.

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12
Q

Use your knowledge about insulation to give reasoning why only the top layer of a lake freezes.

A

Because the ice acts as an insulator for the water and life beneath.

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13
Q

Define convection and provide an example.

A

Transfer of heat in a liquid/gas due to less dense, warmer matter rising and denser, cooler matter falling. Because there is more space between particles, the density changes and hot air is less dense so it is pushed upwards by cooler air, creating a convection current. Eg. The room quickly gets hot when you turn on a heater with the help of convection currents.

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14
Q

Define radiation and provide an example.

A

The movement of heat in the form of electromagnetic waves. Eg. heat from the Sun that warms the Earth that travels through empty space to reach us. This infrared radiation is transmitted as invisible waves.

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15
Q

What is a possum skin cloak? How does it keep you warm?

A

A cloak made from possum skin made by the Aboriginals.
The hair on the possum skin traps heat to warm your body. This is because it has air pockets that trap air. Because air is a poor conductor, it keeps your heat from escaping.

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16
Q

Define sound

A

Form of energy produced when something vibrates, moving back and forth very quickly. It relies on vibrating particles so that it can pass through solids, liquids and gases.

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17
Q

Define sound waves

A

The movement of alternating compressions and rarefactions. These waves travel away from the source in a ripple motion.

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18
Q

Explain the areas of a sound wave.

A

At times, surrounding air particles are bunched together in regions or spread out. Bunched up areas in a sound wave are called compressions. Spread-out areas are called rarefactions.

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19
Q

In what way is sound transmitted through materials

A

Longitudinal waves.

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20
Q

TRUE OR FALSE? Sound travels faster through warm air than cool air

A

True. Warm air vibrates faster.

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21
Q

What state of matter transmits sound faster?

A

Solid because it is more dense as its particles are closely packed and can transfer the vibrations quicker.

22
Q

Compare what happens when sound hits a hard surface and a soft material.

A

Hard surfaces reflect sound and is heard as an echo. Soft materials absorb sound and converts it into heat, reducing reverberation (how long a sound can be heard for)

23
Q

Define frequency. What is it measured in?

A

The number of waves/vibrations a sound makes per second. This is measured in hertz (Hz) - Don’t count the imcomplete ones at the start and end in a diagram.

24
Q

Define wavelength. What is it measured in?

A

The distance between two peaks or troughs next to each other. Measure in metres.

25
Q

Define amplitude. What is the amplitude of a loud sound and a soft sound?

A

Distance between the peak or trough of a wave and the middle positon that affects the loudness of the sound. A loud sound has steep peaks (high amplitude) A soft sound has smaller peaks (low amplitude)

26
Q

Define pitch

A

How high or low a noise sounds. A sound that is produced by a source vibrating quickly has a high pitched. A source that vibrates slowly has a low pitch. (look at frequency)

27
Q

How does the cochlear implant work?

A

It mimics the way the cochlea receives sound. A mic and speech processor is placed behind the ear that pick up sounds and then convert them into electrical signals sent to teh implant in the skull connected to the cochlea which stimulates the auditory nerve to send messages to the brain.

28
Q

Describe the effect that repeated and prolonged exposure to loud noise has on a person’s ears

A

It can destroy delicate sensory cells in the inner ear that detect vibrations and send electrical signals to your brain. They cannot be replaced and you won’t be able to hear. This can also lead to tinnitus.

29
Q

What is tinnitus?

A

A condition in which a person hears a permanent ringing in their ears.

29
Q

What is tinnitus?

A

A condition in which a person hears a permanent ringing in their ears.

30
Q

How is loudness measured?

A

Decibels (dB)

31
Q

Define light

A

Form of energy called electromagnetic radiation. Eg. X-rays, infrared radiation, UV light, microwaves and radio waves.

32
Q

Contrast luminous with non-luminous objects

A

A luminous object is one that emits light. Non-luminous objects can reflect light, but not emit it.

33
Q

Define reflection

A

Light bouncing off objects.

34
Q

Compare regular reflection with diffused reflection

A
  • Light reflects off a smooth surface and the rays reflect in the same direction, producing a clear image.
  • Light reflects off a rough surface and the rays scatter in many directions, not forming an image.
35
Q

State the law of reflection.

A

An incoming ray of light will hit a surface and reflect at the same angle it hit it.

(angle of incidence = angle or refraction, i = r)

36
Q

Define refraction

A

The bending of light that occurs when it travels from one transparent substance to another.

37
Q

Why does light bend differently based on the medium.

A

If it has a higher refractive index then it will travel slower and the medium is denser so it will bend towards the normal and r will be less than i.

If it has a lower refractive index then it will travel faster and the medium is less dense so it will bend away from the normal and r will be more than i.

38
Q

How does the bionic eye work?

A
  • A camera sends information to a video processor
  • VProcessor sends electrical signals to a receiver which stimulates the retina to send messages to the brain.
39
Q

What is the refractive index?

A

A measure of how easily light travels through a substance.

40
Q

A measure of how easily light travels through a substance.

A

Transparent object that is shaped to curve outwards or inwards. It refracts light and focuses it to form images in the eye and in devices such as cameras.

41
Q

Compare convex and concave lens.

A

Convex curve outwards so the light rays converge to produce a magnified image. Concave curve inwards so the light rays diverge to produce a smaller image.

42
Q

Why can magnifying glasses be used to burn a hole?

A

Because they use convex lens that join all the light rays so that they all focus on one area.

43
Q

Flow diagram of how the eye works.

A

Light enters eye through pupil and is refracted by cornea -> Focused by lens onto retina -> Specialised cells called photoreceptors, rod and cone cells, convert light into electrical signals. -> sent to brain through optic nerve.

44
Q

Define cornea

A

Transparent covering over the iris that refracts light into the lens.

45
Q

Define optic nerve

A

Carries electrical signal to the brain.

46
Q

Define electromagnetic waves

A

Perpendicular waves combining the electric and magnetic fields. They are produced when the electric charge vibrates or accelorates.

47
Q

is AM radio transverse or longitudinal?

A

Longitudinal

48
Q

mogus

A

gingus

49
Q

Is sound transverse or longitudinal?

A

Longitudinal.

50
Q

Among us

A

Sus

Pearson Science • Year 9 Sem 2 (3 decks)

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