Science y9 Flashcards
(20 cards)
What is the Law of Conservation of matter
matter cannot be created or destroyed but changes state or form.
What is The Law of Conservation of energy
energy can never be created or destroyed. It can only be converted from one form to another.
What is Heat
Heatis the transfer of thermal energy between objects with different temperatures (always flowing from the high-temperature to the low-temperature).
What happens when Substances are Heated (Particles??)
Adds energy to its particles (causes them to vibrate and move)
Some energy can be stored as potential energy
Heat energy increases the kinetic energy of the movement.
What is temperature
Temperatureis a measure of how hot something is (amount of kinetic energy)
Measured inCelsius(°C),Kelvin(K),Fahrenheit(°F),
Remember, we have to compare heat and temperature in the exam
:))))
Contrasting heat and temperature
Heat refers to the transfer of thermal energy from a hot object to a cold one whereas temperature is a measure of how much kinetic energy the object has (how hot it is).
Conductors?
Substances that transfer heat easily are conductors.
Insulators?
Plastic, air, cloth, wood and rubber are poor conductors of heat and can sometimes block heat transfer completely.
Convection?
As air is heated, its particles gain energy and move further apart.
This hot air is less dense than cool air, so it is pushed upwards by cooler air around it.
Heat is transferred by convection in liquids and gases because their particles can move around.
Creates a convection current.
Raidation?
Radiation is the transfer of heat that does not reply on contact the energy can travel through empty space( a vacuum)
Heat travels through empty space between the Sun and Earth.
Transverse Waves?
Particle movement is at right angles to the motion of the wave.
This is similar to waves in the ocean
Examples of transverse waves are heat radiation & light energy
Longitudinal Waves?
Longitudinal wave particles vibrate forward and backwards in the direction of the wave (parallel to the wave). They form areas of compression (close together) and rarefaction (far apart).
e.g Sound waves
Electromagnetic spectrum?
All the range and frequencies are placed on a spectrum.
There are low-energy waves and high-energy waves.
High frequency electromagnetic waves can be harmful to human health
Higher energy = higher frequency = shorter wavelength
Visible light
Plants absorb the light and make carbohydrates for animals
Visible light is made of different colours – like a rainbow.
Each colour has a different wavelength, blue has the shortest and red has the longest.
Light Energy
Is a form of electromagnetic radiation
It travels as a transverse wave, in a straight line
Light energy that our eyes can detect – white light – is referred to as the visible spectrum
White light is a combination of all the different colours of light (visible spectrum)
Each colour of light is a wave with a different wavelength & frequency and therefore different energy
Contrast heat and light energy
Heatis a form ofkinetic energythat travels slowly through matter as one atom vibrates against another, whereas light energy is a form of electromagneticradiation that travels faster through matter and can travel through a vacuum.
How Light Interacts with Matter
it can be reflected, refracted, absorbed or transmitted.
Classifying matter in terms of Light
Opaque - does not let any light pass through
Translucent - transmits and scatters light.
Transparent - transmits light without scattering it.
