• Registered: 2022-01-21
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Topic: A Level nostalgia and thoughts on batteries

Nostalgia and long past youth. I suddenly remembered taking my A Level Physics Practical exam; the written part was done at school, but for the practical we had to go to the Imperial College Examination Halls just behind the South Kensington Science Museum.

We were each allocated two of a number of experiments set out in  a laboratory there, and I was happy to get an electrical experiment. There was something under cover of an upturned box, and I had to find out what it was with a couple of bits of electrical equipment in the open. There was a voltmeter and  I think one of those beautiful wooden boxes with resistors brought up to brass strips on top - you fitted a tapered brass key to short out two strips and hence the resistance inside. No rotary switches then. It was obvious from measurements that there was a 2 v accumulator inside with a series resistance.

Everyone knows what a car battery is, generally a 6 cell overall 12 V lead/acid battery. If you go back to your youth you may remember the line up for a bettery wireless set: A big box 120V carbon/zinc battery tapped at 30V intervals, for HT+ or plate power rail; a slim 9V  battery tapped at 1.5V intervals for Grid bias: and a glass single cell 2V lead/acid battery "accumulator" with screw terminals for the radio valve filaments.

This accumulator was fitted with a handle as it had to be taken regularly to a (often) bicycle shop to be recharged. The shop may have had DC 250 V instead of AC mains, and its charging station might be a panel with a number of incandescent light bulbs for current limiting.

Ah, it was a lifetime ago.

PS, on reflection, the resistance may not have been a resistance box, as the current through such a precision instrument from the accumulator could be destructive. And the battery may have been one of those enormous cylindrical carbon/zinc cells used for bell circuits. But then, I wouldn't have been able to introduce chat about the lead/acid accumulator in wireless sets.  But again, use of a lead/acid cell would have the advantage of a low series source resistance, making the experiment easier to set up.

2 Reply by GB

  • GB
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  • Registered: 2022-01-22
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Re: A Level nostalgia and thoughts on batteries

My two experiments were Joule's Law and thermal conductivity. In the former, I ended up with 4.17 joules/calorie. The other involved, I seem to recall, using Callender's apparatus, but I cannot recall the details. I know I ended up second in the class - rather to the surprise of Mr Chaundy, our physics master!

3 Reply by jackneve (edited by jackneve 2022-05-31 10:03:29)

  • Registered: 2022-01-21
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Re: A Level nostalgia and thoughts on batteries

I know I ended up second in the class - rather to the surprise of Mr Chaundy, our physics master!

Ah, I beat you! I came first, and received the William Rogers Senior Science Prize. I didn't know I had that honour until I visited my school a few weeks into the Autumn term, and was told - Oh, Jacobs, you've won a prize, expect you here for Prize Giving.
I admit I was gloating somewhat, as having passed the requisite number of A Levels, I had become eligible for a grant and had started my course in Telecommunications and Radio at the Northern Polytechnic. Being normally conservative in habit, I went resplendent in College Scarf and with Blazer badge. Several of my former classmates needed three passes at A Level, and failing one, had to stay on into a third year in the sixth form. My friends had to face me, a nondescript person, bearing  the glory of achieved college life. It wasn't then so easy getting what was called a Major County Exhibition (College & University fees and admission) and a maintenance grant.

I met a girl in the 1st year 6th form at another school soon after this, at my school's old boys dance - and the rest is history. She is still looking after me, after a four year courtship during my college years and 64 years of happy marriage.

I am forever grateful to The Central Foundation Boys' Grammar School and the Northern Polytechnic for the opportunity to move from a poor working class home to a professional life.

BTW, those college style scarves, they were a delight. Most students did wear them in those days, and you knew their college by the colour of the longitudinal stripes. They were very long, and wide, and often were worn with one end over the shoulder. Made of wool , they were warm in winter.  I wore mine out eventually. My NP scarf  was green with two white stripes bordered with dark blue. I also had a London University scarf - I can't remember what colour that was, except it might have had a red element.

I hope you don't mind me reminiscing this way, no class war intended! And just a little boasting.

The Science prize I mentioned I took as three volumes of plays by George Bernard Shaw, with whom I was taken at the time. I still have them.

4 Reply by jackneve (edited by jackneve 2022-05-31 10:01:09)

  • Registered: 2022-01-21
  • Posts: 382

Re: A Level nostalgia and thoughts on batteries

ps Callender's apparatus>

https://utsic.utoronto.ca/wpm_instrumen … apparatus/

or

http://www.goelscientificinstruments.co … 14992.html
This is a calorimeter experiment, I would think more suited to A Level physics than the  other, which seems rather more complex in concept.