Help with Transposition of Formula..

Hey guy's,

I was hoping someone could help me? I've currently studying for my level 2 Electrotechnical Technology and i'm doing well in all aspects of theory and practical. However, i'm REALLY struggling with Transposition of Formula. It make's no sense to me whatsoever. Now it's really important that i get my head around this as i'm sure you all know but it seem's however much i try or people try and explain to me.....it ain't happening.

Is was hoping someone could dumb it down for me(as if you were explaining to a 12 year old) and make it easy for me to understand.

Any help/advice would be gratefully received

Cheers

Mark

Mark there are a few posts on here showing transpositions of forumlas.

AndyGuiness Drink

give me an example and i will try and help you...

I used to think of it in terms of moving something from one side to the other reverses it's function, so if it's multiplied on the right move to the left and divide etc.

eg V=IR

to find R we move it over to left and V/I = R

to find I we move it over to the left and V/R = I

is this what you mean?

If the formulas got three things in it like V= I x R you can put them into a formula triangle... Draw a triangle then then divide it into two by drawing a line across the centre of it then draw a line down the middle of the bottom section of the triangle.

Put the V in the top section, the I in the bottom left section and the R in the bottom right.

To find I cover the letter I, your left with V over R thus I = V/R

To find R cover the letter R, your left with V over R thus R = V/I

If there's more than three things in the formula this doesn't work and confuses me totally too!!! Hope this helps.

Welcome to the forum.

Transposition really screwed me up when I first started at college. It is important to get your head around it at the early stages. I'm assuming if you are in year 2 you are now starting to do 3 phase calculations using root 3 and power factor correction cosines. The easier power triangles would probably have been covered in year one (ohms law).

There really is no easy way to explain it on here, only you know what your weakness is and you should discuss this with your science lecturer or even better, a maths lecturer.

If you don't get on top of it now it will really haunt you if you go on to do HNC or even a degree.

I hope this helps!

Remember everything when you first try to learn is difficult.

I remember many sleepless nights worrying about such things.

As Matt said give us an example, that way we can show you step by step rather than give you a classroom definition, which your tutor has failed to convey to you, or made you understand.

hey every one. I see that these posts are quite old but im hoping to get some help on the same subject. iv been sparky'ing now for a long time and thought i should actually become a registered Electrician.

so im 36 and sitting in class remembering how much I hated school when I get this transposition question

" Calculate the cross sectional area of an aluminium conductor that has a resistance of 0.0516ohms and is 75 meters long. (Resistivity of al at 20degrees concious is 0.0283microhm metres."

now i know the formulato get the resistance is R=pl/a so if i do the triangle formula thing here is it going to work? as in a=pl/r ? i cant find any other examples in my txt books

a=o.0283unm*75/0.516=4.113

Absolutely right.

If you put it into the "formula triangle" it looks like:


So cover up the term you want to be the subject of the formula, and what's left is the answer.

So in your case cover up the a, and you get pl /r

This works for any simple formula

Just remember the opposites ie if you multiply one side then you move it over to the other side of the equation and divide it.

Try and get it in your head as when you get to things like working out capacitance etc you will get stuck.

Get the basics right and it will fall into place and don't worry too much we have all been there.

I hated transposition of formulae & equations & took me ages to get the hang of it at college (failed maths at school), ended up buying the old GCSE exercise books & doing extra maths during college lunch times.

I remember the lecturer telling me to remember BIDMAS(as in solve an equation in this order; expand Brackets Indocies Divide Multiply Add Subtract & what ever you do to one side of an equation = sign you must do to the other side also, with the aim of getting the unknown value one side & the constant value the other side..

Make sense? no then take a look at the vid it explains it rather well.....

Maths Tutor

Best thing I did the extra maths tutoring as I can actualy do my teenagers top level maths homework..........still dont know the times tables parrot fashion though

Another way to look at it would be to note that whatever is done to one side of the equation has to be done to the other.

If you have an equation, for instance V = IR, then whatever you do to the left-hand-side (LHS) has to be done to the right-hand-side (RHS). For instance if you want I on its own, you have to divide it by R. Whatever you do the RHS has to be done to the LHS, giving you V/R = I.

A lot of people seem to struggle with algebra, and I genuinely believe that if it was taught from a younger age we wouldn't have that problem.

Practice makes perfect, so just play around with various formulae and it'll become second nature.

It can be confusing and it also depends on the rules you use

As an example of how confusing, (for those that use windows)

Open the calculator and do 5 - 3 * 4, you get 8

now click on view and change to scientific

do 5 - 3 * 4, you get -7

I do know why, but it does make for confusion.

Hi Guys,

Can someone help me make L the subject from the below please?

i= v_s/R (1-e^((-Rt) ⁄ L)

Welcome.

Although we are here to try and help; we aren't here to solve your homework for you

It usually seems to work best if you have a go at it, and show us your working out, then we can help with your understanding of the concept, rather than just solving your problem, if you see what I mean?

Once you understand the concept, you'll be able to transpose any formulae yourself.

Try.......

Well, to me anyway, it does not look like you have copied the formula out correctly

Can you post a link to where you hot the formula from in the first place

v_s. Looks wrong to start with.......but it was a F long time ago since i did PURE , and Advanced maths

Probably all done on them new fangled Abacus things now

kerching said:

Well, to me anyway, it does not look like you have copied the formula out correctly

Can you post a link to where you hot the formula from in the first place

v_s. Looks wrong to start with.......but it was a F long time ago since i did PURE , and Advanced maths

Probably all done on them new fangled Abacus things now

Click to expand...

one of these???



:innocent

pie?

mmm pi...

3.142?

round the 5 up and you get 3.142...