The heater uses a power of 2.8 kW. Calculate the current in the heater.
The wiring in the cable from the socket and in the boiler will stay safe and will not overheat as long as the current is less than 20 A. Suggest a suitable fuse rating for the circuit.
The specific heat capacity of water is $4200\,\text{J kg}^{-1}\,^{\circ}\text{C}^{-1}$. The heater is used to raise the temperature of 6.3 kg of water. Over a certain time, the water temperature rises from 23 ^{\circ}C to 49 ^{\circ}C. Calculate the change in the internal energy of the water.
The heater transfers thermal energy to the water at a steady rate. It takes longer for the water temperature to rise from 49 ^{\circ}C to 75 ^{\circ}C than from 23 ^{\circ}C to 49 ^{\circ}C, even though the temperature rise is the same in both cases. Suggest why it takes more time for the temperature to increase from 49 ^{\circ}C to 75 ^{\circ}C.
Fig. 10.1 places the heater at the bottom of the water in the boiler. Explain how thermal energy is transferred from the heater throughout the water.
The section of the boiler that contains the water is made from steel. Describe, in terms of particles, how thermal energy travels through the steel.
State and explain, in terms of particles, what happens to the density of the steel as its temperature rises.