P1 1-8 Flashcards
What is temperature?
It tells us how hot something is and is measured in degrees Celsius (°C) . It is a measure of the average kinetic energy of the particles in a substance.
What is heat?
A form of energy , measured in Joules . It is a measure of energy on an absolute scale.
What affects the rate of energy temperature?
The difference in temperature between the object and its surroundings.
What is specific heat capacity?
the amount of energy in joules needed to raise the temperature of 1 kg of the material by 1 °C.
What is specific latent heat?
The amount of energy (in joules) needed to change the state of 1 kilogram of a substance
What is the difference between specific latent heat of fusion and vaporisation?
The specific latent heat of fusion (for melting a substance) is not the same value as the specific latent heat of vaporisation (for boiling and evaporating a substance).
What is conduction? How does it work?
Energy is transferred through solid materials by conduction. The particles in a solid are always vibrating. When the particles are hotter, they have more energy and so vibrate more.
When you heat one end of an object, the particles start vibrating more and collide with other particles. Kinetic energy is transferred from one particle to its neighbours.
Why are some materials good thermal conductors?
Energy is conducted through them easily. Their particles are close together in a regular pattern and so the vibrations are passed on easily.
Why are some materials good thermal insulators?
The particles are close together, but the pattern is not as regular as in a metal. This means that energy only passes slowly from one particle to another.
Why are liquids and gasses poor thermal conductors?
The particles in a liquid are not in any regular arrangement, so it is much more difficult for the energy to be passed on by conduction. In a gas, the particles are far apart so gases are very poor conductors.
How do free electrons help energy transfer in metals?
The free electrons gain more kinetic energy from collisions as the metal is heated. They transfer the energy very quickly as they travel through the metal.
What is convection?
When moving particles carry energy from one place to another
What is infrared radiation?
the transfer of energy by electromagnetic waves.It does not need a medium to travel through.
How does the surface of an object affect how much energy it absorbs or emits?
A dark matt surface is good at absorbing infrared radiation. A light-coloured or shiny surface is bad at absorbing infrared radiation.A dark matt surface is also a good emitter of infrared radiation and a light or shiny surface is a poor emitter of infrared radiation.
How does a cavity wall work?
If there is nothing in the wall cavity but air, the air can move around and transfer heat from the inner wall to the outer wall through convection. The cavity is filled with an insulating material. This is usually something with small pockets of trapped air. This makes use of air as a good insulator, but prevents loss of heat through convection as the air cannot form a convection current.
