Help with Electronics Questions

jack.mitchell

jack.mitchell

jack.mitchell

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Joined
15 Apr 2008
Posts
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Location
West Didsbury, Manchester
So, I've got resits coming up in September for university and i'm trying to hack my way through a Circuits & Systems paper. My uni have been gracious enough to provide me example question papers but no solutions. Therefore I thought I would ask here if someone who is more qualified in this area could help me make my way through it. I've already done this question and got answers but it would help if I could get clarification to see if i've done them correctly, i'm not asking anybody to do my exam questions for me (what would be the point?). Anyway below is a screenshot of the question and my answers:

gUf4nl.jpg.png

1.

i) 0.625 ohms

ii)

A-B = 8A
R1 = 1.875A
R2 = 3.675A

I think I have i) and ii) A-B right but i'm not sure on the others, any help would be appreciated!
 
When I did my HNC at college I was provided with question papers and answers to them by the college, with the OU I was able to purchase them through the student union.... I would've thought you should be able to do this?
 
We have a library of past papers that anyone can access at our uni. Occasionally the lecturers put up the answers.

Anyway, I've just had an exam very similar to that module you're doing (EG1050).

All I can say is, I despise any electrical and electronic engineering of any sort so sorry, I'd rather not attempt a solution :p.

Thank god for specialisation in 3rd year (mechanical, the first two years here are general engineering, so has electrical/electronic parts).
 
If you redraw it, it makes it simpler.

I'm sure there's various theories on how to solve these that make it easier, but I did finished my electronics degree 3 years ago and became an accountant... so I've forgotten everything.

Anywho - i get:

625

8mA
5mA
3mA

But I could be wrong....
 
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0.625KR= 625R (breaks down to 2 equivalent parallel resistors of 1K and 1.667K).

Total current: 8mA (5V/625R)

R2 = 3mA (1/2.667KR * 8mA)
R1 = 5mA (1.667/2.667KR * 8mA AND 1.667KR * 3mA)

(Substitute .667 for 2/3)

I'm technically an electronic engineer, there's a bit of paper on my wall that says so and I'm 95% certain they are right!
 
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Skyrunner said:
Yes well I broke it down in to unit resistors to simplify it, I simply forgot to factor the 1000 back in ;-)
Click to expand...
Too easy to make!

To the OP: You did the hard bit! All the current has to go through either R1 or R2, so due to something that Kirchoff theorised on that I can't remember and/or common sense dictates that the sum of the currents through both of those are going to have to equal the 8 (i.e. 5 + 3).

How did you arrive at your two figures?
 
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Yes I agree with the others,

625Ohms,

8mA
5mA
3mA

Worked it out myself to prove I could still do it (nuclear physics is my trade, but I did a helluva lot of electronics in my degree too!). :)
 
Ahh OK, I get it guys, much clearer now. I'm slowly getting my head round it, whats annoying is that I can put the theory into use in practise but shove an exam in front of my face expecting you to do things a certain way then I find it difficult. I may come back with more yet but I'll see how i get on. Thanks again.
 
csmager said:
Too easy to make!

To the OP: You did the hard bit! All the current has to go through either R1 or R2, so due to something that Kirchoff theorised on that I can't remember and/or common sense dictates that the sum of the currents through both of those are going to have to equal the 8 (i.e. 5 + 3).

How did you arrive at your two figures?
Click to expand...

KCL and KVL.

Urgh :(
 
csmager said:
If you redraw it, it makes it simpler.

I'm sure there's various theories on how to solve these that make it easier, but I did finished my electronics degree 3 years ago and became an accountant...
Click to expand...


How did you manage to get into accountancy. Did you do accountancy courses?
 
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