On the podcast they were talking about why does a microwave spin?
Well i thought i would answer that here incase anyone was wondering. But i learnt this in my AS Level Physics classes.
Basically what happens in a microwave is microwaves are shot out of the slot on the side, and they are a certain wavelength which will create "Hot spots" and "Cold spots" on the food, the spinning of the plate causes these hotspots to overlap and reach all of the food to distribute the heat evenly and cook the food evenly. If this turning doesn't happen and you cook something from frozen, you can get parts that are extremely hot, and others that are still frozen.
A small experiment that you can do at home, is take the spinner out. Get a microwave safe tray and fill it with marshmallows. Then put it in the microwave for 2-3 minutes and take it out. Doing this you can see where the hotspots of the microwave are by the melted marshmallows. By taking the distance between the hotspots you will get the half the wavelength of the microwave. Double this to get the full wavelength
Now that you have the microwave length, you can find the frequency of your microwave, most are about 2450mhz, and from this you can calculate the velocity of light. If your microwave is 2450 MHZ then the space between hotspots should be about 6cm. Doubling this gives you 0.112M Adding in your MHZ 2450Mhz X 0.112m This gives you the speed of light at 274 400 000 m / s which is within about a 5% error margin of the actual speed of light.
I do A level physics too but I was never taught this, that's really cool :D And I'm assuming the 'grate' infront of the microwave door is to stop too much of the polarised microwaves from escaping. And if you try to use your phone or try and watch a video on your laptop near it when its on, you temporarily lose all connections, which is pretty fun as I piss my parents off when they bring their technology into the kitchen XD
It doesn't generate heat, instead it's firing rays which bounce around the chamber for the food. When one of those rays passes through the atomic structure of your food it causes the particles to vibrate and thus generate heat via friction.
Additionally if you place your food as close to the outside of the spinning platter as possible, the chance of those rays hitting your food is higher than if you place it in the center. Liquified cheese is a great material to experiment with food placement to find the optimal distance from center in a microwave since it coagulates when over cooked.
As for escaping radiation. Hak5 has a great demonstration of how to pick up ambient signals in the 2.4GHz to 2.5Ghz spectrum. The program they demonstrate for doing this comes as part of Backtrack Linux (which can be booted from a CD or USB stick), it graphs signals in the same spectrum as the 802.11 wireless specifications. Turn on a microwave with the graph recording and it spikes harder than if you were monitoring the spectrum at a hacking conference.