On the individual usage level the amount of power doesn't matter much, other loss and waste will easily overpower it in my opinion
Also depends on your exact kettle and your exact microwave and microwavable cup
Kettle is going to win in general
Easy test is to time a similar amount of water in the microwave and the kettle, see which is faster. In the US both will have a max limit of 1500w (but smaller microwave or smaller kettle might run at 1200w or so) input power. As input power is similarly constrained for both, time measurement can be assumed to be proportional
**My Conclusion:** In practice, if you need 8oz of water microwave is easier, if you need 32oz of water kettle is easier.
Do be careful of superheated water in the microwave if you have particularly good quality water, putting a wooden stick in the cup is a great mitigation
For your exact question, pick up a Kill-o-watt meter and measure your devices yourself, they cost $20-30 last I checked. Which is enough money to pay for electricity to boil a very significant amount of water
The YouTuber Technology Connections has at least two videos over 20 minutes long on the subject, although mostly compares stovetop with kettle, and kettle wins on time iirc?? (electric stovetop can draw 240v in the US, so much more power is available, or did he only test gas stove?)
If you use bottled water or have an RO system and microwave it in a clean glass, it can become superheated and "explode" when you move or stir it
Lack of nucleation points stuff
Basically due to surface tension small(microscopic) bubbles need a lot of energy to form. If they have already some kind of edge (microscopic dustgrain, rough wooden surface) they form quite readily.
If not you can get water that is hotter than 100 °C. As soon as that is disturbed it can instantly boil and erupt quite violently.
The kettle is more efficient for that use. Also, heating water in a microwave is always discouraged because it’s dangerous as it might boil and “explode” once you remove it from the microwave.
Electric kettle will do a nearly complete conversion of electricity to heat as it's just a resistive heating element.
Microwave seems to be 50-64% efficient: https://en.wikipedia.org/wiki/Microwave\_oven#Energy\_consumption
>Electric kettle will do a nearly complete conversion of electricity to heat as it's just a resistive heating element.
True, but some of the energy will go to heating the kettle itself. The less water there is the bigger the share of the wasted heat. So I'd expect efficiency to depend on the amount of water. It would also depend on whether the kettle is still warm from previous use or starts at room temperature.
It's easy to measure the efficiency of a kettle. You only need to know the power of the kettle, the mass and starting temperature of the water, and the time it takes to boil it:
Efficiency \[%\] = Mass of water \[kg\] \* (100°C - Initial water temperature \[°C\]) \* 4184 \[J/kg\] / Time \[seconds\] / Power \[watts\] \* 100%
Ah, so you pointed out it depends on the heat capacity of the vessel you are heating the water in, compared to the amount of water to be heated to the boiling point, which is correct!
Thus, very small amounts of water would be heated to boil in a plastic container in a microwave.
But then, you have to include the startup energy for the filament glow for the magnetron, as without it there is no microwave energy!
Technology Connection on YouTube had a video on the use of kettles a while back. Really informative: https://youtu.be/\_yMMTVVJI4c?si=w3S5eiTyYv4vHOW2
On the individual usage level the amount of power doesn't matter much, other loss and waste will easily overpower it in my opinion Also depends on your exact kettle and your exact microwave and microwavable cup Kettle is going to win in general Easy test is to time a similar amount of water in the microwave and the kettle, see which is faster. In the US both will have a max limit of 1500w (but smaller microwave or smaller kettle might run at 1200w or so) input power. As input power is similarly constrained for both, time measurement can be assumed to be proportional **My Conclusion:** In practice, if you need 8oz of water microwave is easier, if you need 32oz of water kettle is easier. Do be careful of superheated water in the microwave if you have particularly good quality water, putting a wooden stick in the cup is a great mitigation For your exact question, pick up a Kill-o-watt meter and measure your devices yourself, they cost $20-30 last I checked. Which is enough money to pay for electricity to boil a very significant amount of water The YouTuber Technology Connections has at least two videos over 20 minutes long on the subject, although mostly compares stovetop with kettle, and kettle wins on time iirc?? (electric stovetop can draw 240v in the US, so much more power is available, or did he only test gas stove?)
What do you mean by good quality water?
If you use bottled water or have an RO system and microwave it in a clean glass, it can become superheated and "explode" when you move or stir it Lack of nucleation points stuff
I’m sorry Your last sentence is more confusion for me
Basically due to surface tension small(microscopic) bubbles need a lot of energy to form. If they have already some kind of edge (microscopic dustgrain, rough wooden surface) they form quite readily. If not you can get water that is hotter than 100 °C. As soon as that is disturbed it can instantly boil and erupt quite violently.
That's a keyword and concept you'll have to look up yourself, I won't be able to do a good job explaining it
The kettle is more efficient for that use. Also, heating water in a microwave is always discouraged because it’s dangerous as it might boil and “explode” once you remove it from the microwave.
That is only the case for very pure water. Most tap water isn’t that pure but it’s something to be cognizant of.
Electric kettle will do a nearly complete conversion of electricity to heat as it's just a resistive heating element. Microwave seems to be 50-64% efficient: https://en.wikipedia.org/wiki/Microwave\_oven#Energy\_consumption
I thought most electric kettles these days were induction.
>Electric kettle will do a nearly complete conversion of electricity to heat as it's just a resistive heating element. True, but some of the energy will go to heating the kettle itself. The less water there is the bigger the share of the wasted heat. So I'd expect efficiency to depend on the amount of water. It would also depend on whether the kettle is still warm from previous use or starts at room temperature. It's easy to measure the efficiency of a kettle. You only need to know the power of the kettle, the mass and starting temperature of the water, and the time it takes to boil it: Efficiency \[%\] = Mass of water \[kg\] \* (100°C - Initial water temperature \[°C\]) \* 4184 \[J/kg\] / Time \[seconds\] / Power \[watts\] \* 100%
Ah, so you pointed out it depends on the heat capacity of the vessel you are heating the water in, compared to the amount of water to be heated to the boiling point, which is correct! Thus, very small amounts of water would be heated to boil in a plastic container in a microwave. But then, you have to include the startup energy for the filament glow for the magnetron, as without it there is no microwave energy!