unit 5 - thermal effect Flashcards
(29 cards)
structure of solid
fixed structure
molecules held very closely by strong forces
can vibrate backwards and forward but cannot change position
structure of liquid
irregular structure ( shape of the container )
molecules are close together and attract each other
they can slide past each other
structure of gas
no fixed structure
molecules well-spaced, weak forces between them
move freely and fast and can collide with each other and wall of the container
what are two fixed points in the thermometer?
0 and 100 degree celcius
what is calibrating
putting a scale on an instrument
how to put a scale on a thermometer
put the thermometer in the melting ice, wait until the thermometer value to decrease and mark the point
put the thermometer in the boiling water, wait until the thermometer value to increase and mark the point
divide the distance between two points into 100 equal divisions
how to improve sensitivity in the thermometer
the narrower the tube, the higher the sensitivity
what is the range in the thermometer
the lowest and the highest temperature that the thermometer can measure
how to increase responsiveness in thermometer
thinner glass in the bulb
what is the linearity of the liquid in the thermometer
the expansion to increase in temperature is linear
describe thermal expansion
when the object gets heated, the particle gets speed up. their vibration takes up more space so the object will expand slightly.
what happens to the volume of the gas if the temperature increases
volume increases
what happens to the pressure in the sealed tube if the temperature increases
pressure increases
what is conduction
thermal energy is transferred from the hot end to the cold end as the faster particles pass on their extra motion to particles all along the bar
what is another word for poor conductor
insulator
why metal is a good conductor
they have free electrons that get speed up when they are heated and they collide with atoms and make them vibrate faster.
what happen to the density when the water get heat up
the density decreases because volume expands
which factors increase the energy radiated per second
surface temperature and area
what colour is the best emitter and absorbers
black
what colour is the best reflector
silver
feature of vacuum flask
stopper ( like a lid) to reduce conduction and convection
vacuum gap to reduce convection or conduction
silvery surface to reduce radiation
difference between evaporation and boiling
evaporation
- can happen at any temperature
- only happen on the surface
boiling
- only happens at boiling point
- happen throughout the whole liquid
what affects the rate of evaporation
temperature, surface area, humidity, presence of wind across the surface
how evaporation gives a cooling effect
as the particle evaporates, it takes energy away
