Recent content by Edwina Lee

Point taken, thanks Dale!

Ah-ha! So there is a thick clunky ventilation tube connecting to the outside.

That must be it. They are only evaporation coolers.

I just chatted to Currys' adviser, and he told me there is no connecting pipe to the outside. So I told him I'll ask a science forum why it works.

I am seeing lots of brands of home portable air conditioners to cool rooms. They are sold through well known nationwide chains such as Currys, Argos in the UK. Customer feedback shows that they really work. But why would they work??? Surely, these portable aircons need to take away heat from...

This is what you said in #2: "You would just get a bigger black hole. The no hair theorem implies that there is no distinction between black holes made from different constituents. " Could you now explain why what you said is in conflict with what I said in #5: <<" I thought that the joining of...

The 1st thing to bear in mind is what quantities do you want to know about and to input. This way you get a set of variables relevant for your modelling. You could try building something simple first, then add on more complexity.

I thought that the joining of an anti-matter particle with a normal particle of the same mass results in 0 mass, and the energy released is ##2mc^2## where m is the mass of each particle. So as 2 black holes of opposite matter approach each other, we should start to see energy release caused by...

Short of unscrewing the motor or do a photograph from the outside, I discovered that it is a KDK 25AUH (25 cm extractor fan). It has an HP condenser motor, so I guess it can only run on a narrow range of voltage - i.e. single speed.

So, the next question is curiosity. Why do some fan motors cannot run at different voltages? And would it get damaged if a lower voltage is used to try to run it?

Thanks jrmichler. Unfortunately, I cannot access it as the motor is on the outside of the high rise. :rolleyes:

My mother has an alternating current extractor fan plugged into the mains. I want to run it at different speeds. I am thinking of using a light dimmer switch to deliver variable voltage to control the fan speed. (An electrical engineer friend told me that it is possible only if the fan is...

I want to make my own set of molecular models with balls representing atoms and links representing bonds. Anyone knows of a good software to do this? As for the physical model, what bond angles, bond lengths and ball sizes should I create? I could for example leave atoms as round balls and...

There is a huge gap of knowledge about genetic modification between the public and those pushing it. So I like to know answers to the questions that are top of my mind:- [1] The technique of genetic manipulation depends on a certain virus to bind to DNA to cut and insert. Can this virus...

Jerromyjon, Berkeman, tech99, Thanks for your response. I don't have technical information other than from general news channels. (SCMP.COM is a Hong Kong english paper. You can read a limited number of their articles for free by registering.) Their article gives some details about the...