# Amperage change with power level

**URL:** <https://boards.straightdope.com/t/amperage-change-with-power-level/119376>\
**Category:** Factual Questions\
**Created:** [July 17, 2002, 8:04am UTC](https://boards.straightdope.com/t/amperage-change-with-power-level/119376 "2002-07-17T08:04:59Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\
**Post date:** [July 17, 2002, 8:04am UTC](https://boards.straightdope.com/t/amperage-change-with-power-level/119376/1 "2002-07-17T08:04:59Z")

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Does the number of amps my microwave draws change with the power level? An electrician told me that it doesn’t, but this doesn’t seem right to me.

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**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\
**Post date:** [July 17, 2002, 8:25am UTC](https://boards.straightdope.com/t/amperage-change-with-power-level/119376/2 "2002-07-17T08:25:58Z")

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The power levels of a microwave are obtained by cycling it on and off so the _average_ goes down but the _peak_ remains the same.

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**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\
**Post date:** [July 17, 2002, 1:10pm UTC](https://boards.straightdope.com/t/amperage-change-with-power-level/119376/3 "2002-07-17T13:10:58Z")

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Some newer microwaves actually adjust power output rather that cycling the full power for varying percentage of cooking time. I think Pansonic has one that does this.

They should draw less current at the lower power settings.

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**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\
**Post date:** [July 17, 2002, 1:45pm UTC](https://boards.straightdope.com/t/amperage-change-with-power-level/119376/4 "2002-07-17T13:45:39Z")

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> [@](#):
>
> \*Originally posted by dtilque \*  
> \*\*Does the number of amps my microwave draws change with the power level? An electrician told me that it doesn’t, but this doesn’t seem right to me. \*\*

This site says [The current changes with power setting](http://www.howstuffworks.com/framed.htm?parent=microwave.htm&url=http://www.gallawa.com/microtech/how_work.html). So your electrician is mistaken.

The power tube of microwaves is a magnetron. The magnetron puts out a series of microwave pulses, _i.e._ it turns on and off, waits a while and then turns on and off again, etc. The power output during the pulse, the peak power, is the same at all times. As an example, suppose the magnetron is on 10% of the time, and off 90%. Then the average power, which is what determines how fast the food cooks, is 10% of the peak power. If the same pulse on time and the same peak pulse power are maintained and the pulse repetition rate is reduced so that the ratio of on to off is reduced to 8%, the average power has been cut by 12.5%. And so on.