Chapter 3- Heat, Light and Sound Flashcards
What does heating a substance do?
Adds energy to the particle
What happens when an object is heated?
The particles start to vibrate more and more and also expand as they move apart
How do substances change state?
When the particles vibrate so much that they break free from one another and change state
What is conduction?
How heat travels through solids
How does conduction work?
Hotter substances have particles that vibrate faster and as heat flows from areas of higher temperature to lower, the particles cause other particles to vibrate and the heat spreads.
What are conductors and insulators?
Conductors are substances that transfer heat easily. Insulators are substances that are poor conductors or even block heat completely
What are some examples of good conductors?
Metals e.g Gold, Nickel, Iron
What are some examples of good insulators?
Plastic, air and cloth
How does a thermos flask work?
They create a vacuum between the substance inside and the substance outside, meaning that heat cannot get inside
What is convection?
How heat travels in liquids and gases
How does convection work?
As air is heated, and because hot air is less dens than cool air, causing it to rise, the airflow of the rising and falling air creates an airflow called a convection current
What are some examples of convection?
Things like sea breezes and hot water systems
What is radiation?
Because space is a vacuum, heat from the sun cannot be transferred through conduction or convection because there are no particles so it transfers through radiation.
How does radiation work?
The heat transmits itself as an invisible wave that travels at the speed of light and is known as an Infrared (IR) wave
What happens when radiated energy hits a surface?
It is either absorbed, reflected or transmitted depending on the substance and colour
What type of colours absorb, reflect or transmit?
Dark colours absorb heat, light colours reflect and clear materials transmit hea
How is sound produced?
When vibrations create compressions and rarefractions
What substances can sound transmit through and what can it transmit through the best?
It transmits through solids the best, then liquids, then gases and not at all through a vacuum because it relies on particles to move
How does a transverse wave move? And what are some examples?
Up and down or side to side. Examples are light waves and secondary waves
How does a longitudinal wave move and what are some examples?
Back and forth in the same direction the wave is travelling and examples are sound waves and Primary Waves
What speed does sound travel at through normal air temperature?
Around 340m/s
What type of surfaces reflect sound and what is it heard as?
Hard surfaces such as concrete reflect sound waves and it is heard as an echo
What types of materials absorb sound?
Soft materials such as carpet
How does sonar work?
The sound reflect off a hard surface and is heard as an echo and the time difference can be used to calculate the depth of something underwater
What produces a higher pitch or frequency?
The faster the particles vibrate
What is frequency?
The number of vibrations a sound makes per second. It is measured in hertz
What is the wavelength?
The distance between two crests or trenches
What is amplitude?
How loud a sound is and the larger the peak of a wave, the higher the amplitude
What is the relationship between frequency and wavelength?
Sound that have a higher frequency produce sound waves with a shorter wavelength
What is the equation for a wave?
Velocity (which is always the same) which equals Frequency times wavelength
What are the parts and their functions of the outer ear?
The Pinna which funnels sound into the ear canal
The Eardrum which vibrates the sound and separates the outer and middle ear
What are the parts and their functions of the Middle ear?
The Ossicles- 3 bones (hammer, anvil and stirrup) that magnify the vibrations
Oval Window- Transmits vibrations to the cochlea and separates Middle and Inner Ears
What are the parts and their functions of the Inner Ear?
Eustachian Tube- Connects to the nose and throat and controls the air pressure which stops the eardrum from bursting
Semicircular Canals- Control our sense of balance
Cochlea- Vibrations are detected by tiny hairs in the cochlea which convert the movement into electrical impulses
Auditory Nerve- Transmits the electrical impulses to the brain
What types of things are used to fix hearing?
Hearing Aids magnify the sound and enable people to hear better.
Cochlea implants replace the cochlea and can fix deafness
What can happen when light hits a surface?
It is either transmitted through it, reflected off it or absorbed into it
What happens when light hits a transparent object?
Almost all light is transmitted through it and a clear image can be seen through it. E.g clear glass or shallow water
What happens when light hits a translucent material?
Some light maybe be reflected and light that passes through it is scattered, an image can be seen through it but it is fuzzy. E.g. Tissue paper, frosted glass
What happens when light hits an opaque material?
Light is either reflected from or absorbed into the surface. No light is transmitted and no image can be seen through it. E.g brick, wood etc
What is the law of reflection?
Angle of incidence equals angle of reflection
What is the ‘normal’?
An imaginary line that goes through the middle of the two Rays
What happens when a plane mirror produces an image of an object?
It creates a virtual image
When does light refract?
When it travels through substances of different optical density
Why does light refract?
Light travels at different speeds through different substances and the difference in speed results in different amounts of bending
What happens when light enters a denser substance?
It bends towards the normal and slows down
What happens when light enters a less dense substance?
It bends away from the normal and speeds up
A lens that bulges outwards is called a?
Convex lens
What do convex lenses do to light rays?
They cause the light rays to come together or converge
Do convex lenses produce virtual or real images?
Real images
What type of lens do we have in our eyes?
A convex lens
A lens that curves inwards is called a?
Concave lens
What do concave lenses cause light to do?
Diverge or spread out
What times of images do concave lenses produce?
Virtual images
What are the parts of the eye?
Cornea, Iris, Pupil, Sclera, Aqueous Humour, Lens, Ciliary Body, Vitreous Humour, Retina, Optic Nerve
How does light travel through the eye?
It is refracted by the cornea and goes through the pupil to the lens where it is focused as a clear upside-down image onto the retina which turns in into electrical impulses and sends it to the brain via the optic nerve
What is the function of the cornea, sclera, Iris and pupil?
The cornea refracts the light into the eye
The Iris enlarges and shrinks the pupil to control light flow
The pupil is a hole that determines amount of light allowed in
The sclera is the white of the eye
What is the function of the aqueous humour, lens and ciliary body?
The aqueous humour is a clear liquid that separates the lens and cornea
The lens focuses the light onto the retina
The ciliary body changes the shape of the lens
What is the function of the vitreous humour, retina and optic nerve?
The vitreous humour is the clear fluid between the lens and retina.
The retina converts light into electrical impulses
The optic nerve carries electrical impulses to the brain
