Which one of the following statements about heat is correct>
? It passes from cold objects to hot objects.
:-) It passes from hot objects to cold objects
? The more the heat flow the higher the temperature.
? Objects only radiate when they reach a temperature of at least 100 degrees Celsius
What do we call the process in which heat passes through a solid material
:-) Conduction
? Convection
? Radiation
? Insulation
Which one of these describes a solid material that blocks the flow of heat.
? Conduction
? Convection
? Radiation
:-) Insulation
The Sun passes its heat to the Earth by:
? Conduction
? Convection
:-) Radiation
? Insulation
A small crystal of potassium permaganate (purple dye) is placed at the bottom of a beaker of water. The beaker is heated, and the purple dye is seen to rise. This is due to:
? Conduction
:-) Convection
? Radiation
? Insulation
In an experiment, the top of a boiling tube of water is boiled. A temperature probe connected to a computer is at the bottom of the boiling tube. It registers hardly any change in temperature. The correct reason for this is:
? the computer or the temperature probe has probably failed.
X a reverse convection current has been set up to cool the bottom of the tube.
? radiation only starts to occur at the boiling point of water.
? that water is a very bad conductor of heat.
The best kind of heat sink for a transistor (an electronic component) consists of:
? just a single flat piece of bare metal.
:-) metal shaped into a set of fins, coloured black.
? metal shaped into a set of fins, coloured silver.
X plastic shaped into a set of fins, coloured black
On a hot humid day, large clouds may form due to:
? radiation from the Sun.
? conduction of heat through the air.
:-) convection currents of air heated by the hot land.
? difference in air pressure at ground level and high up.
Animals in cold regions tend to be bigger than animals in hot regions. The reason for this is that:
? they have a low surface area to volume ratio, so they lose heat less quickly and stay warm more easily.
? there are more food sources about.
X there is stronger radiation from the Sun, so they warm up quicker
? they have black skin so they can loose heat more quickly.
Heat radiation is called:
? Ultra violet
? Ultra red
? Infra violet
:-) Infra red