Temperature and heating
What instrument is used to measure temperature?
A thermometer.
What is the main way energy is transferred through a metal pan?
Conduction.
Why is wood used for a pan handle?
Because it is a good insulator of heat.
Which kettle is more powerful if it boils the same amount of water in less time?
The kettle that boils it faster.
In a lawn mower, name one way energy is wasted.
By heating or by sound.
What is the boiling point of water?
100°C.
What is the main way energy moves around a warm room from a radiator?
Convection.
In an insulation experiment, which material is best at keeping water warm?
The one with the highest final temperature.
What is power a measure of?
How quickly energy is transferred.
What does a Sankey diagram show?
How energy is transferred usefully and wasted.
In which direction does thermal energy transfer between a cold can and warm air?
From the warmer air to the colder can.
Which type of energy transfer is being tested with black and silver thermometers near a ray box?
Infrared radiation.
Why is trapped air a good insulator?
Air is a poor conductor, so less energy is transferred.
Complete the equation: energy use = ___ × time
Power rating.
Which machine is more efficient on a Sankey diagram?
The one with the bigger useful energy arrow and smaller wasted arrows.
After a cold drink is left in a room for several hours, what will happen to its temperature?
It will reach room temperature.
Why does a black thermometer heat up faster than a silver thermometer?
Black surfaces absorb infrared radiation better.
Give one reason a lid helps water boil faster.
It reduces heat loss to the surroundings.
A 1.5 kW heater is used for 6 hours. What is the energy use?
9 kWh.
What does payback time mean?
The time it takes for savings to cover the extra cost of a more efficient product.
Why does a pan with a thicker base keep bubbling for longer after the heat is turned off?
The thicker base stores more thermal energy, so it keeps transferring heat to the water for longer.
Explain conduction in a metal using particles.
Particles in the hot part vibrate more and transfer energy to neighbouring particles, so energy passes through the metal.
Why does a wet cloth help keep food cool?
Water evaporates from the cloth, and the highest-energy particles escape, taking energy away and cooling the food.
Give one way to reduce the energy used for heating at home.
Any valid example, such as using insulation, lowering the thermostat, or heating for less time.
Give one advantage to people and one to the environment of using more efficient electrical machines.
People save money on bills, and less energy is wasted so there is less environmental impact.