Question for any bright spark

[Lee1987]

Hi everyone,

Im a qualified electrician but am now re-training to be an Overhead lines man and have basically got to do another apprentiship, Im doing a course called MOL (manchester open learning) and the course is similar to my old apprentiship, Im struggling with remembering some formulas and am trying to complete a practice paper, heres a question I am struggling with as I cant seem to find the formula I need, any help much appreciated;

a 15 H Coil (inductor) carries a current of 7 A. What amount of energy is stored in the magnetic field?

Thanks
Lee

 

[telectrix]

E = LIsq./2. in this case (15 x 49)/2 = 367.5j

edit: i forgot as well, so i looked it up. why couldn't you?

 

[Silly Sausage]

E = LIsq./2. in this case (15 x 49)/2 = 367.5j

edit: i forgot as well, so i looked it up. why couldn't you?

I thought we're not allowed to dish out the answers anymore?

 

[ackbarthestar]

The simple answer would be : E = 1/2 * L * I^2

 

[ackbarthestar]

You lot are quick .....lol

 

[telectrix]

was feeling generous today

 

[ackbarthestar]

Just reading through my old notes

We also have: W = 1/2 * B*H* field volume or W = (B^2 / 2Uo) * Field volume

 

[telectrix]

now it's definitely beer time.LOL.:leaving:

 

[Lee1987]

Appreciate your help very much, have been looking it up but with limited success, plus im not good with all the theory, just the hands on work.

Thanks again
Lee

 

[Silly Sausage]

Just reading through my old notes

We also have: W = 1/2 * B*H* field volume or W = (B^2 / 2Uo) * Field volume

Tip for Lee, with these questions, look at what they give you in the question and what quantity is required, then look at the equations and see which fits the information you've been given.

 

[Lee1987]

Yeah thanks all

Your right Archy, I really need to make up a list of all the formulas as I appear to have lost (thrown away) all my old notes from my old apprentiship

 

[Silly Sausage]

Yeah thanks all

Your right Archy, I really need to make up a list of all the formulas as I appear to have lost (thrown away) all my old notes from my old apprentiship

Buy one these...only £2.81!
Amazon.co.uk: Used and New: Hughes Electrical Technology

All the equations you'll ever need. I still refer to my battered old 6th Edition

 

[Top Cat]

I was going to answer this but it only applied to bright sparks so didn't bother!

 

[parker56]

after 4 cans I don't feel a bright spark, more like a happy spark.lol

 

[Top Cat]

after 4 cans I don't feel a bright spark, more like a happy spark.lol

See you are from Devon, went on my holls last week to Devon lovely part of the world.