An electric heating element consists of a metal wire that becomes very hot when an electric current passes through it. The middle of the wire is at a very high temperature, whereas the ends of the wire connected to the terminal blocks are much cooler.
Which statement is correct?
Thermal energy is conducted from the hot middle of the wire to the cooler ends.
The electrical resistance per unit length is lower in the middle of the wire than at its ends.
The wire radiates thermal energy at the same rate at all points along its length.
If the current through the wire is halved, the power output of the heating element is halved.
301 exam-style questions on CIE IGCSE Physics 2.3 Transfer of thermal energy, covering 2.3.1a Thermal conductors and thermal insulators, 2.3.1b Explaining thermal conduction, 2.3.2 Convection, 2.3.3a Thermal radiation, 2.3.3b Surface colour and texture, 2.3.3c Rate of emission and absorption of radiation, and 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.