How do I know if microwave is working correctly?

I bought a Sharp microwave about six months ago.

I use it mainly for heating up stuff, and for de-frosting meat.

I've noticed, when heating up baby's bottles or milk for children's cereals/hot chocolate, that the time taken to heat, say, 200 ml of milk to a hot-ish temperature can vary from 30 seconds to 80-90 seconds. I don't know why this varies so much.

The obvious reason would be that the containers used are of different materials, and permit the radiation of heat at different rates. However, we only use the one brand of bottle, (though some bottles are newer than others.) I always use the top level of power (900W).

Short of marking each bottle, beaker and cup in the house and testing them individually, is there any way I can check that the microwave is working correctly? While the heating thing is a nuisance (and drives the baby spare ), it's the defrosting of stuff like chicken and mince that concerns me, from a food safety point of view.

I'm not sure I have an answer re your microwave, but to address your issues:

The defrosting shouldn't be that big an issue as you are going to cook the meat anyway.

I always understood that bottles shouldn't be microwaved? I never used artificial milk myself but when necessary expressed, bottled breast milk was easily warmed up in a jug of hot water.

Yes I have always heard that it is safer to warm formula in a jug of hot water....because the liquid heats from the centre outwards and any small particles of formula that are not completely dissolved and are sitting towards the centre of the fluid can get extremely hot...

When I defrost I check chicken pieces every couple of minutes and keep moving it around as otherwise I find the edges can start to cook a little. With mince I defrost for a minute or two and remove the outer defrosted layer onto a dish and return the still frozen piece to the microwave and repeat until it has defrosted right through.

Thanks for the input. I was actually referring to full-fat (ie regular) milk, as the 'baby' is a burly 14-month-old who has just been weaned.

Isnt it supposed to be recognised as dangerous these days to eat food microwaved in plastic ? I saw a few articles which said it creates carcinogenic free radicals

bullworth said:

Isnt it supposed to be recognised as dangerous these days to eat food microwaved in plastic ? I saw a few articles which said it creates carcinogenic free radicals

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Can you give some references? I've never heard that.

I know the news articles bullworth is referring to....it was fairly recent....can't find it at the moment but this link has some similar information....
http://bodyecology.com/articles/microwave_dangers.php

Ceepee said:

Can you give some references? I've never heard that.

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With a toddler myself it concerns me. It might depend on the type of plastic and I'm not an expert but a lot of worrysome stories like the above article have popped up from time to time which claim that cancer-causing compounds from plastic containers and plastic wrap can leach into your food when microwaved.
About 6 weeks ago there was a couple on The Afternoon show on RTE (or whichever show occupies that RTE daytime 3/4pm slot) who had trouble conceiving after a long time trying and the ''expert'' brought into the show was helping them change their diet and also advised them to stop microwaving food in plastic to improve their fertility. So there seems to be a lot of issues with microwaved plastic.... fertility issues, carcinogens etc.