Final answer:
Heating water increases the rate of diffusion of tea because higher temperatures increase molecular movement. Doubling the voltage to an immersion heater would reduce the heating time but is not recommended due to safety concerns. Heat transfer methods like conduction, convection, and radiation are applicable in various scenarios.
Step-by-step explanation:
Heating water affects the rate of diffusion of substances like tea. This is due to the fact that higher temperatures increase the energy and movement of the molecules, leading to a higher rate of diffusion. When you heat water, the water molecules move more rapidly and mix with tea more quickly, causing the tea to diffuse faster.
If the voltage applied to an immersion heater is doubled, assuming the resistance of the heater does not change, the power, which is proportional to the square of the voltage (P = V2/R), will also be quadrupled. This would mean that the time required to heat water would be reduced, as you're delivering more power to the heater. However, significant safety concerns arise when increasing the voltage beyond the appliance's design, such as the risk of electrical fires or damaging the heater. Therefore, doubling the voltage is not a good idea from a safety standpoint.
The diffusion of tea in water also relates to various methods of heat transfer such as conduction, convection, and radiation. Conduction is observed when holding a hot cup, convection when steaming milk, and radiation when making Sun tea with the heat of the sun. These mechanisms contribute to the overall energy transfer within the system.