END OF YEAR SCIENCE TEST

Catch the waves:

A wave is a movement of energy from one place to another.


Oscillation is a backwards and forwards (or up and down) movement from two points. The middle of the motion is where the particle would be if no energy was passing through the substance.


A shadow is made by blocking light. Light travels in straight lines. If an object gets in the way, it stops light from travelling through it. This makes an area of darkness appear behind the object-a shadow.


A wave can be described by frequency. The frequency of a wave is how many times it makes the particles in the substance it is travelling through oscillate every second. While sound waves require particles to oscillate, light waves are electromagnetic waves—they consist of oscillating electric and magnetic fields and do not require particles or a medium to travel.

Frequency is measured in hertz, Hz


Sounds change if the frequency changes. It the frequency gets higher, meaning that the particles in a substance oscillate more times in a second, the sound has a higher pitch and vice versa.


The parts of a human ear are:

-Pinna (outer ear)

-Ear Canal

-Ear drum

-Ossicles

-Cochlea (which is filled with fluid)


Air particles are vibrating (oscillating) because of sound waves. Vibrating air makes the ear drum vibrate. The vibrating ear drum makes the 3 tiny bones in the ear move. The moving bones make waves in the liquid of the cochlea. The waves in the liquid make hair cells move. The hair cells send signals to the brain.


Light changes if its frequency changes. If light waves have a different frequency the will have a different colour. Light frequencies are very big.


The electromagnetic spectrum consists of 7 types of light.

-radio, which is used to broadcast radio and TV

-microwaves, used in cooking, radar, telephone and other signals

-infrared, transmits heat from sun, fires and radiators

-visible light, makes things able to be seen

-ultraviolet, absorbed by the skin, used in fluorescent tubes

-X-rays, used to view inside of bodies and objects

-gamma rays, used in medicine for killing cancer cells

Heat is thermal energy; infrared is electromagnetic radiation emitted by hot objects.

X-rays are used to see inside the human body.

Gamma rays have the most energy, the more energy the higher the frequency.

The kind of light my cellphone uses to send text messages are radio waves and potentially microwaves.


Atoms make light when their electrons jump from a higher energy level to a lower energy level and release a packet of energy called a photon.


Sounds change if their amplitude changes. They get louder or quieter.

Light also changes if its amplitude changes. Light gets brighter or darker (intensity changes) but will remain the same colour.


Light travels much faster than sound.


A lightyear is used to measure distance in space. One light-year equals about 9.46 trillion kilometers Light moves at about 300,000 kilometers per second. This is because space is so big.


An echo is formed when An echo is caused when a sound wave travels through the air, hits a hard surface, and bounces back to your ears


Lateral inversion is the effect where an image in a mirror appears flipped from left to right, even though it stays right-side up.


Coloured objects appear the way they do because their chemical and molecular structures absorb certain wavelengths of light and reflect or scatter others into our eyes.



Atomic adventures:

Definitions:


Period

-A horizontal row of elements on the periodic table going from 1-7

Group

-A vertical column of elements going from 1-18


Neutron

-A neutral particle found in the nucleus

Proton

-A positively charged particle found in the nucleus

Electron

-A negatively charged particle found in the electron shells


Metal Alloy

-Two or more metals combined


Viscosity

-the tendency of a liquid to resist flowing.

-high viscosity=flows slowly eg. honey

-low viscosity=flows quickly eg. water

Conductivity

-A material’s ability to let heat or energy flow

-high conductivity=flows easily e.g. copper

-low conductivity=doesn’t transfer heat or electricity well e.g. wood

Malleability

-the ability of a solid to be hammered or shaped without shattering

-high malleability=is easily shaped/flattened e.g. aluminium

-low malleability=is brittle e.g. ceramics

Ductile

-The ability of a solid to be drawn into a wire

-Highly ductile=becomes wire easily e.g. copper

-low level of ductility=cannot easily become wire/at all e.g. glass

Hardness

-Can the material scratch something else?

-Relative term harder than ____ softer than ____

-e.g. metal vs. wood

Melting Point

-a physical property describing the temperature at which a substance changes from a solid to a liquid

-e.g. ice→water at 0*C

Boiling Point

-a physical property describing the temperature at which a substance changes from liquid to gas

-e.g. water→water vapour at 100*C

Density

-when a material is heavy or light for its size

-e.g. rocks sink, buoys float

Lustre

-The way an object looks when light reflects off of it (shiny or dull) aka. pretty

-e.g. a mirror possesses lustre, wood does not

Solubility

-The ability to be dissolved, especially in water

-e.g. salt is highly soluble, but sand is insoluble


Physical Property

-can be observed without changing the composition of the substance

-e.g. colour, size etc.

Chemical Property

-describes how a substance behaves during a chemical reaction

-e.g. dissolves, ignites, combines etc.


Calculating

-Electron=same number as atomic number & protons

-Proton=same number as atomic number & electrons

-Neutron=mass number - atomic number


Heat Energy:

Conduction

  • the transfer of heat through direct contact

  • energy moves from hotter to cooler

  • can occur in solids, liquids and gases

Convection

  • the transfer of heat by the movement of liquids or gases e.g. lava lamp, oceans, air

  • only occurs in liquids and gases

Radiation

  • the transfer of heat by electromagnetic waves e.g. sunlight to Earth

  • (space is a vacuum, no particles)

  • thermal radiation is invisible


Black surfaces

  • excellent absorbers and emitters of thermal radiation

  • they absorb most incoming heat energy

  • also lose heat quickly by radiation

White surfaces

  • are poor absorbers and poor emitters

  • reflect most radiant energy


This means that black containers heat up faster in sunlight, but white containers stay cooler for longer, keeping the contents inside hotter for longer.


Heat transfers energy to particles, always moving from hot to cold.


Water is the only thing that can exist in all 3 states of matter naturally.


Key words

  • insulator

  • conductor

  • particles

  • heat transfer

  • touching

  • conduction

  • convection

  • radiation

  • vibrating particles

  • gaining energy


Gas

  • can be compressed easily due to lots of space between particles

  • particles are far apart and have no forces holding them together

  • do not have a fixed shape or volume

  • particles are moving very fast in all directions

  • can condense into liquid


Liquid

  • take up the shape of the container they are in but have a fixed volume

  • difficult to compress as the particles cannot be pushed much closer together

  • can evaporate into gas

  • can also freeze into a solid


Solid

  • cannot be compressed as particles are already very close together

  • has a fixed volume and shape

  • some solids (e.g. ice) can be melted into a liquid


Everyday Insulators

  • double/triple glazing (has air pockets between layers, air is a great insulator)

  • a puffer jacket (has goose down, microscopic air pockets, air is a great insulator)

  • bubble wrap (again with the air pockets)


Everyday Conductors

  • aluminium

  • brass

  • copper

  • iron