You CAN melt glass in a microwave (microwaves explained) - Filmed from the inside #3

[Music] i figured out how to film inside a microwave this is the third video in that series and it's melting glass [Music] glass generally doesn't melt in a microwave you can use it as a receptacle to heat your beverage it's considered to be microwave safe but it is possible if you really want to all you have to do is heat the glass first i'm using a blow torch i'm going to heat a large area first and then focus on one spot that's just to prevent thermal shock what you saw at the beginning of the video was sped up here it is in real time so so this experiment is a good illustration of why it's not always easy to defrost something in a microwave to see why think about the way a microwave works you probably know that a microwave is good at heating up water so water is h2o it's an oxygen and two hydrogens like this model that i've got here so there's the oxygen there's the hydrogens this is a covalent bond so there is some electron sharing going on here and the oxygen pulls on those shared electrons more strongly than the hydrogens do meaning that the oxygen ends up with a little bit of negative charge and the hydrogens end up with a little bit of positive charge so this is a polar molecule it's called polar because it has charges at different ends so what happens when you put a molecule of water in an electric field well an electric field is just a way of showing an area of influence around a charged particle so if i've got a proton here for example that's positively charged and i've got another proton here this proton is going to feel a force from this one a repulsive force because like charges repel so i can draw field lines around this proton that show its influence over this charged particle here and by convention you draw field lines in the direction in which a positive charge would feel a force so if we set up an electric field around this water molecule we don't need to worry about what's generating the field like you could have you know some positively charged particles down here and some negatively charged particles up here and then we've got field lines pointing upwards well if the field is pointing upwards then the positive charge end will be drawn upwards and the negative charge end will be drawn downwards so the molecule will reorient itself like this so if i then change the direction of the electric field so it's pointing downwards then the molecule will reorient itself again so the positive end will point downwards and the negative end will point upwards microwaves are electromagnetic waves which means their oscillations in electric and magnetic fields so as a microwave passes over a molecule of water the molecule of water finds itself in an oscillating electric field so it's constantly reorienting itself like this it's gaining kinetic energy and that's what heat is heat is just atoms and molecules with kinetic energy so microwave ovens work on substances that are polar like water that's why you can't heat up oil very easily in a microwave oil molecules aren't very polar so what happens when you've got ice well with ice you've got water molecules locked into a crystal lattice structure where they can't move so if i put frozen water in an electric field well the oxygen will want to move upwards and the hydrogens will want to move downwards but they can't because they're locked in place by the lattice and what that means for a microwave is that as microwaves pass over the frozen water when they pass over the ice the molecules won't move they won't absorb energy they won't absorb those microwaves so how can you defrost anything at all well when you take food out of the freezer like this carrot for example it will start to defrost of its own accord because it's now at room temperature it will defrost from the outside in and so you'll find that just by chance some point on the outside of the carrot defrosts before any other part and so you have a small patch of liquid water from then on all the microwaves are absorbed by that small patch of liquid water and so you can see it boils very very quickly even though the other end of the carrot is completely frozen so what you're left with is a carrot that's boiling hot at one end and frozen at the other this is why the instructions on a microwave meal usually tell you halfway through to give the ingredients a stir that's to redistribute the heat that's really clumped together in in just a few spots the same logic applies to glass glass is mostly silicon dioxide which isn't a polar molecule because silicon dioxide doesn't form molecules it forms a kind of covalent network but the silicon oxygen bonds are polar but just like with ice those atoms are locked in position it's not a crystal lattice like with ice it's an amorphous solid but the rules still apply those atoms can't move when uh microwaves pass over them when you have that alternating electric field but if you heat the glass up enough then those atoms start to get a little bit of movement and they can start to absorb those microwaves and eventually start to melt [Music] so that's how you melt glass in a microwave i'd like to thank audible for sponsoring this video since getting into audiobooks i've spoken to a lot of people who do audio books and someone said to me you've listened to harry potter of course and i said no because i mean i've i read harry potter when when the books came out so why would i listen to the thing when i've when i've already read the thing and he said you know it's read by stephen fry and it's amazing and it is amazing it's like the perfect combination harry potter and stephen fry so i'm enjoying those books all over again i'm up to book four already they're really really good if you want to enjoy harry potter read by stephen fry for free or indeed any book from the audible range they have the best range you can sign up for a 30-day free trial go to audible.com forward slash steve mold or click on the link in the description if you do that really helps me out because they know that i sent you i hope you enjoyed this video if you did don't forget to hit subscribe and i'll see you next time you

Channel: Steve Mould

Views: 279,823

Keywords: explained, understand, radiation, electromagnetic, electric field, water, ice, oscillation, amorphous solid

Id: xwEQZw3KPWg

Length: 9min 17sec (557 seconds)

Published: Thu Jun 22 2017