Question

If the kettle contains 1.4L of water initially at room temperature (20∘C), what's the time until the water begins boiling?

Answer 1

It is possible to calculate the energy required to boil the water from the given information. However to find the time until the water begins boiling, the rate at which energy is applied must be known. For example, if the heating is by an electrical element, the power rating of the element is needed.

Answer 2

I mean, do you actually increase the temperature at some point or what?

Answer 3

it will start to boil only when you add energy into the water, other than that, it can't be higher than the temperature (average) of the room.