Test your physics

[parallelepipete]

8 - stonking hangover tho'

Smoke detector radiation, really

I wonder if there will be panic amongst test-takers as they realise there is a nugget of americium-241 sitting in every other room in their home. Shock, horror!

 

[parallelepipete]

9/10. It makes no difference which way blue and brown are wired!

I'd never even considered that before, but that's a good point! I assume the colours of the two conductors are different so people don't end up wiring up their houses* with half brown, half blue attached to sockets' live terminals. That might produce interesting results...

* Which will be illegal for DIYers to do anyway from next year, I think?

 

[MikeMcc]

9/10. It makes no difference which way blue and brown are wired!

It does if you get a short, the device could still be live! Also motor driven devices such as fans may drive in the wrong direction (a phase rotation fault).

Mind you, the UK is one of the few countries that has a mains distribution system in a house that is designed to be fail-to-danger, the good old ring main. If you get a break in the wiring, both parts of the circuit will continue to be supplied and you may not even be aware that you have a potentially lethal fault present!

 

[Ich bin ein Mod]

10, but then it was pretty simple. Wish that'd been my tests at uni

 

[parallelepipete]

It does if you get a short, the device could still be live! Also motor driven devices such as fans may drive in the wrong direction (a phase rotation fault).

Mind you, the UK is one of the few countries that has a mains distribution system in a house that is designed to be fail-to-danger, the good old ring main. If you get a break in the wiring, both parts of the circuit will continue to be supplied and you may not even be aware that you have a potentially lethal fault present!

So why was the ring main adopted? Just because it shared the load between two conductors rather than one in a radial design?

 

[gentlegreen]

I wonder if there will be panic amongst test-takers as they realise there is a nugget of americium-241 sitting in every other room in their home. Shock, horror!

Isn't there an urban myth somewhere of someone who collected enough smoke detectors together for a DIY fission reactor ?

 

[parallelepipete]

Isn't there an urban myth somewhere of someone who collected enough smoke detectors together for a DIY fission reactor ?

I hadn't heard of that. I wonder what they'd do with all the plastic shells!

*rings Tate Modern*

 

[kyser_soze]

6/10...altho I got 20/20 on the maths and English tests...and haven't done physics since GCSE...

 

[MikeMcc]

So why was the ring main adopted? Just because it shared the load between two conductors rather than one in a radial design?

Fault tolerance in a less enlightened age! Each supply point would continue to work even if the main became severed.

I don't know what the regs are for new builds - I would have thought that they would have gone for radial designs now.

 

[gentlegreen]

Isn't there an urban myth somewhere of someone who collected enough smoke detectors together for a DIY fission reactor ?

just did a google and onre estimate for the number of smoke detectors required for a bomb are in the order of 10^11

.

 

[Dr Jon]

9

Put Infra-red for smoke detectors without thinking. Mind you, it is 5:45 am here...

 

[electric.avenue]

Must brush up me physics.

8/10 for the physics, full marks for the maths and the english. Looks as tho I'd better brush up my physics as I'm taking A2 this yr (mature student). Got an A last yr in the AS .

One of the ones I got wrong was that smoke detector one.

Thanks for pointing me in the direction of those bbc quizzes - fun.

 

[Blagsta]

8/10
I got confused between longitudinal and transverse waves and I didn't know it was alpha radiation in smoke detectors.

 

[Epona]

9/10 - I can't do even the simplest of sums in my head, I just go blank - it was the maths that fucked me up - much like my 'A' Level

 

[Groucho]

6/10

 

[electric.avenue]

So is alpha radiation a stream of alpha particles?

Also, someone mentioned doing the problems in their head. If so, you are genius - I used pen and paper for some of the more complicated maths and physics questions.

 

[electric.avenue]

The two I got wrong were:

the smoke detector one

the transformer at the power station one

I still don't get the transformer at the power stn one. Anyone feel like explaining?

 

[gentlegreen]

The two I got wrong were:

the smoke detector one

the transformer at the power station one

I still don't get the transformer at the power stn one. Anyone feel like explaining?

high voltage / low current uses transmission cables more efficiently than low voltage / high current.

I believe the Japanese use millions of volts rather than hundreds of thousands

.

 

[gurrier]

The two I got wrong were:

the smoke detector one

the transformer at the power station one

I still don't get the transformer at the power stn one. Anyone feel like explaining?

http://en.wikipedia.org/wiki/Ohms_law

 

[Derian]

*gathers belboid, spanglechick, fractionMan, kyser soze and Groucho around her in the 'could do better' physics corner*

 

[laptop]

http://en.wikipedia.org/wiki/Ohms_law

Er... not exactly.

If I remember the question right, you just have to know that power = current * voltage.

And to accept the assumption that there is no power loss in the transformer (meaning that Ohm's Law is not involved, nor are the rather more complicated inductive losses).

So if you step 100 volts with a current of 10 amps up to 2000 volts it's just 0.5 amp...

 

[gurrier]

Er... not exactly.

If I remember the question right, you just have to know that power = current * voltage.

And to accept the assumption that there is no power loss in the transformer (meaning that Ohm's Law is not involved, nor are the rather more complicated inductive losses).

So if you step 100 volts with a current of 10 amps up to 2000 volts it's just 0.5 amp...

I stand corrected

 

[gentlegreen]

http://en.wikipedia.org/wiki/Ohms_law

I find these handy - cover most combinations :-

W = IV, I = W/V etc ...

 

[spiralx]

9/10 - I got the plug thing wrong.

 

[Red Faction]

7/10
tho i do HATE physics

only my second time EVER posting in this forum
and my 1st was to say how much i like polar bears

 

[Derian]

7/10
tho i do HATE physics

only my second time EVER posting in this forum
and my 1st was to say how much i like polar bears

Come and join as at post 50

You might be too brainy for us though