WorksheetsHeat transfer
Total questions: 24
Worksheet time: 40mins
What are the units for measuring energy?
newtons
degrees Celsius
joules
degrees Fahrenheit
If you leave a cup of hot tea standing in the kitchen for a whole day, what will happen?
No energy will be transferred.
It will gain energy from the air in the kitchen.
Energy will be transferred from the tea to the air until the tea is the same temperature as the air.
Energy will be transferred from the tea to the air in the kitchen, so the tea will end up colder than the air in the kitchen.
The amount of thermal energy in an object depends on three things. Which of these things does it not depend on?
its mass
its colour
its temperature
the material it is made from
Which statement about evaporation is not true?
When some of a liquid evaporates, the liquid left is warmer than before.
Evaporation can happen at any temperature at which the substance is a liquid.
When some of a liquid evaporates, it is the particles moving the fastest that escape and form a gas.
Sweating cools us down when the sweat evaporates.
Infrared radiation can travel through:
transparent objects only.
opaque objects only.
empty space only.
empty space and transparent materials.
When one end of a piece of metal is heated:
the particles vibrate less and so the particles get closer together.
the particles vibrate more and the vibrations are passed from particle to particle.
the energy does not move through the metal.
the particles get bigger.
Solids are better heat conductors than liquids or gases because:
the particles are closer together in gases.
the particles are closer together in liquids.
the particles are closer together in liquids.
the particles in a solid cannot move.
Why does the cold air near the ice lolly move downwards?
It is colder and denser than the air further away from it.
It is warmer and denser than the air further away from it.
It is colder and less dense than the air further away from it.
It is warmer and less dense than the air further away from it.
Which list of materials shows only insulating materials?
wool, feathers, copper
feathers, wood, carpets
iron, copper, steel
plastic, aluminium foil, wood
Which statement is the best explanation for why many insulating materials contain trapped air?
trapping the air stops energy being transferred by convection
air is a poor conductor
trapped air makes the material lighter
gases are poor conductors and they cannot transfer energy by convection if they cannot move.
The surface of which material would reflect infrared radiation the best?
white and dull
black and shiny
white and shiny
grey and dull
Which statement is correct?
dark colours are good emitters and absorbers of radiation
dark colours are good emitters and poor absorbers of radiation
dark colours are poor emitters but good absorbers of radiation
light colours are good emitters and absorbers of radiation
What are the units for measuring power?
joules
watts
volts
kilowatt-hours
How can you find the power of an appliance?
see how hot it gets when switched on
see what voltage it needs
look for the efficiency label
look for the power rating on the label
Which kinds of appliances transfer the most energy?
heaters and cookers
lights
TVs and radios
computers
The efficiency of an appliance is calculated by:
comparing the useful and wasted energies
measuring how much energy is transferred
comparing the useful energy transferred to the total energy supplied
comparing the wasted energy transferred to the total energy supplied.
What units for energy are used on electricity bills?
kilowatt-hours
kilowatts
joule-hours
joules
Which of these is not a way of trying to reduce energy bills?
increasing the insulation in your home
using more efficient appliances
using appliances with high power ratings
using solar power to heat water
What does ‘payback time’ mean?
The time it takes to pay off the loan on a new appliance.
How long a new appliance will last without needing repairs.
The time it takes to save enough money on energy bills to pay for a change.
The time it takes a new appliance to reduce your energy bills.
Freezer A costs £200 and freezer B costs
£150. Someone buying freezer A would save £20 per year on energy bills. What is the payback time if someone buys freezer A instead of B?
0.4 years
0.6 years
1.6 years
2.5 years
The energy efficiency shown in this diagram is:
About 10%.
About 30%.
About 60%.
Impossible to tell.
A kettle uses 100J of electrical energy to produce 7J of sound energy and 93J of thermal energy. How efficient is the kettle?
100%
7%
93%
95%
A washing machine uses 250J of electrical energy to produce 125J of useful energy. How efficient is it?
5%
50%
55%
100%
A hairdryer uses 300J of energy to produce 60J of sound energy and 240J of thermal energy. Calculate it's efficiency.
80%
90%
20%
100%
