EduNinjaA copper cooking pan contains water. Fig. 2.1 shows the pan on a hotplate of a cooker.
Fig. 2.1
Copper is a metal.
Thermal energy is conducted through all solids by lattice vibrations.
Describe one other way in which thermal energy is conducted through the copper.
Fig. 3.1 shows a small block of ice floating in a beaker of warm water.
Fig. 3.1
Energy is transferred from the water to the block of ice.
State the name of the thermal process that transfers energy from the water to the ice.
A rod is made half of aluminium and half of glass.
A pin is attached to each end of the rod by wax.
The rod is heated at the centre.
A pin falls off when the wax melts.
Which statement is correct?
Pin P falls off first because aluminium is a better thermal conductor than glass.
Pin P falls off first because aluminium is a worse thermal conductor than glass.
Pin Q falls off first because glass is a better thermal conductor than aluminium.
Pin Q falls off first because glass is a worse thermal conductor than aluminium.
Fig. 4.1 shows a metal pan on an electric hotplate. The pan contains of water.
Fig. 4.1
The pan is heated. The temperature of the water in the pan increases.
Thermal energy is transferred through the metal pan by conduction.
State and explain the two ways that thermal energy is conducted in a metal.
The table shows the state of materials P, Q, R and S, and whether each one contains free electrons.
Using the information in the table, which comparison of the thermal conduction in the materials is correct?
It is better in P than in Q and S.
It is better in Q than in R and P.
It is better in R than in Q and P.
It is better in S than in R and Q.
During a picnic on a warm, dry day, a metal can of lemonade is wrapped in a damp cloth. Evaporation cools the water in the cloth.
As the water in the cloth cools, so does the lemonade.
Explain how electrons transfer thermal energy through the metal of the can.
The diagram shows the gap between a hot surface and a cold surface. The gap can contain air (gas), iron (solid), a vacuum or water (liquid). cold gap
hot
Which material in the gap allows the quickest transfer of thermal energy between the surfaces by conduction?
air (gas)
iron (solid)
vacuum
water (liquid)
In which type of substance are free electrons involved in the transfer of thermal energy?
all liquids
all solids
metals only
plastics only
The handle of a metal saucepan is made of plastic. As the saucepan heats up, the handle gets warmer.
Which statement explains this?
Molecules of the plastic radiate their energy to other molecules.
Molecules of the plastic vibrate more and pass on their energy to nearby molecules.
The free electrons in the plastic transfer the thermal energy along the handle.
The heated molecules very slowly move along the plastic handle.
A bar of metal, which is a good thermal conductor, is heated at one end.
What is the main method of transfer of thermal energy along the bar?
lattice vibration
movement of atoms of the metal along the bar
transfer by electrons
vibration of atoms of the metal bar