Cambridge Secondary (7-9). Stage 9. Science. Learner's Book - Unit 3: Forces and energy - Question 113

The diagram shows a water tank with an electric heater to heat the water.


The total volume of water in the tank does not change. Some tanks have a second electric heater that can be used when not all of the water in the tank needs to be heated. Suggest where the second electric heater would be positioned in the tank.