17th edition ( equations and formulas)

[telectrix]

transpose means to find a value from the other side of the equation. e.g. V=IR, transpose to find R--- R=V/I.

 

[telectrix]

so like with VD eqauation, the formula is VD = mV/A/m x L x A, trranspose to find L for a given VD.

 

[martinh89]

so like with VD eqauation, the formula is VD = mV/A/m x L x A, trranspose to find L for a given VD.

Ahh i see, thanks if its certain thinga including ohms law i should be fine, im sorry if this sounds like a daft question but how would i just find the length in a vd calculation? All the examples ive done, the lenght has always been included in the information

 

[Pete999]

answered by telectrix exactly, dont worry about move on only 2 mins per question. The question was you were given 4 values of vd, if you can't transpose, you wont be the only one, try this trick use the formula
VD=LENGTH X AMPS X mv DROP do it 4 times until the answer matches the right one in the answers given in the question.
Pete999

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Sorry my last and divide by 1000
Pete999

 

[Richard Burns]

These are the only equations likely to come up even tangentially and complex calculations would not be required.
View attachment Equations for Installations.pdf

 

[Guitarist]

Make sure you read the questions carefully. I misread a few and ended up with only 92.something percent. Was gutted at the time.
Very simple really as long as you've digested your 7671. Oh, and a few marker tabs at table pages helps too.

 

[snowhead]

Make sure you read the questions carefully. I misread a few and ended up with only 92.something percent. Was gutted at the time.

It's ones like which IS the correct or which is NOT the correct, except they don't print is and not in bold

 

[telectrix]

Ahh i see, thanks if its certain thinga including ohms law i should be fine, im sorry if this sounds like a daft question but how would i just find the length in a vd calculation? All the examples ive done, the lenght has always been included in the information

easy. transpose. 1000 x VD = mV x A x L, so L = (VD x 1000)/( mV x A )

 

[Geordie Spark]

Make sure you read the questions carefully. I misread a few and ended up with only 92.something percent. Was gutted at the time.
Very simple really as long as you've digested your 7671. Oh, and a few marker tabs at table pages helps too.

A few marker tabs??


I used those coloured Post It notes - so many in fact, my book looked like a grass skirt.

 

[martinh89]

Cheers for all the advice its very much appreciated, ive been studying all afternoon and adding post it notes throughout the book, ive got my test on Thursday so ill let you know how i do