Reed Switch

A reed switch consists of an LCR circuit ( inductor,capacitor and resistor in series). Using a 12volt (50 Hz) AC voltage supply with an 8.5 ohm resistor an inductor coil of .085 Henry and variable capacitance, we can work out the angular frequency of supply as 310 rad/s and thus the reactance of the inductor will be 26 ohm and if the current was 0.42 A then we could calculate the reactance of the capacitor as 53 ohms

A Chemical Oscillator

A mixture of the following three solutions leads to an interesting reaction -
Solution A - 200 mL of water + 200 mL hydrogen peroxide (27%)- dilute to 500 mL
Solution B - 21.5 g Potassium iodate + 400 mL water + 2.15mL conc. sulfuric-> 500 mL
Solution C - 8 g malonic acid + 1.7 g manganese II sulfate hydrate->250mL then add 10mL/ 1.5g sol. starch and dilute to 500mL

Add 50mL of A to 50 mL of B- swirl ( or use a magnetic fly) then add 50 mL solution C

The mixture will go amber then black then colourless and then keep repeating this colur sequence for some time.

The overall reaction is
IO3- + H2O2+ CH2(COOH)2 (in acid) -> ICH(COOH)2 + 2O2 + 3H2O

hypiodic acid is an intermediate and [I-] controls

Gravity never sleeps

Students initial struggle with projectile motion comes from not intuitively realizing that once a force has projected an object that force is no longer contributing to its motion and thus gravity is the only force acting on it: hence the parabolic path in the event of no resisting forces.

I find it pays to refer to the first law as " things like to stay as they are- so when you kick something into motion it will keep going in that direction forever if no other forces act on it. This is where " gravity never goes to sleep " comes in.

Once they accept this concept, I find they have little trouble in using trig to break the initial motion into its vertical and horizontal components.

the solution

Organic compounds that break up into 2 organic moieties on hydrolysis are the esters- therefore compounds B and C are carboxylic acid and alcohol. When B reacted with thionyl chloride, two chlorines were substituted in, so aside from the carboxylic acid group there must have been an alcohol group - i.e. it was either 2-hydroxy or 3-hydroxy propanoic acid. It had to be the 3 hydroxy as 2- hydroxypropanoic acid contins a chiral carbon and therefore would rotate the plane of polarized light( unless it happened to be a 50:50 racemic mixture!)
Compound C ( which is an alcohol) produces oxalic acid( ethandioic acid) on complete oxidation so must have been a 1,2 diol, i.e. ethan-1,2,diol.
The ester of these rwo would be 2hydroxyethyl,(3hydroxy)propanoate-compound C

The last time I went home

I am originally from Ireland and for reasons that I wont go into I seldom go home. I got a phone-call from the brother-in-law. " Are ya comin' home to sat goodbye to your mother, or are ya comin' home to bury her- 'cos she is on her way." " Be there soon", says I.

Arranging travel from NZ to Ireland is difficult at the best times, so over Christmas I finally managed to organise a flight via Tokyo and Franfurt- 1/2 way round the world!
When I went into the duty free in Auckland airport, I saw Irish whisky on special at only $20NZ a bottle- not knowing what the quota was in Dublin I bought half a dozen.
The flights to Tokyo then Frankfurt were long and boring, consuming 3 books and none of the whisky(I was saving that for whatever faced me in Dublin). As I boarded the Aer Lingus flight from Frankfurt to Dublin, there were two types of passengers- a single transit passenger from NZ- and the whole of the Irish symphony orchestra! It was a fun journey as these talented musicians played amusing musical games. On landing in Dublin airport, the whole orchestra, baggage and all disappeared through the VIP entrance and I was left to face the whole of the customs alone.
" Have you anything to declare?" Customs officers in Ireland are like Russian police, big beefy and frightening.
" Er, well I have these six bottles of Irish that I got in Auckland- I'm sorry officer sir but I didn't know the quota(I hate it when I'm reduced to a snivelling grovelling sycophant)
" What the fuck are you doin', bringing Irish whisky into Ireland ya stupid eejit"
" Well officer sir, it only cost about 4 pounds a bottle in Auckland>"
" 4 pounds a bottle??!! Holy mother of Jesus - hey lads lets hire a plane!!!
With that I gratefully slunk away with my booty. I got to say goodbye to mammy and we gave her a good wake with 6 bottles of Irish making a small contribution to prosceedings.
Go mbeirimid beo ar an am seo aris!


Welcome to FC2!

Latest journals
Latest comments
Latest trackbacks
Monthly archive
Search form
Display RSS link.
Friend request form

Want to be friends with this user.