This official sponsor may provide discounts for members

# Hi everyone

Discuss Hi everyone in the The Welcome Forum area at ElectriciansForums.net

P

Welcome to ElectriciansForums.net - The American Electrical Advice Forum

I have just started theCity & Guilds 2330 electrical installation on day release from work.
I am finding some of the maths a bit tricky.Can anyone out there explain to me how the answer to this maths question was reached

R= 17.5X10-9(ohms sign)mX100m
__________________________ =1.9ohms

1.5X10-6m2

the 9 and the 6 after the minus signs are written small in the text book i think they are multiplication factors.

Thankyou.

This official sponsor may provide discounts for members
T

#### tufan

the result of the formula must be

1,16 ohms NOT 1,9

#### LukeScotty

##### -
Arms
Hiya padley1786, welcome to the website and I hope you find your answers on this forum. Keep intouch

E

#### EasyFox

The small 6 & 9 are called numers of Indices or to the power of.
So in your case you have
10-9 or 10 to the power of minus 9
10 -6 or 10 to the power of minus 6

R= 17.5(10-9)x100 / 1.5(10-6)m2

so now it looks like

R = 0.00000175 / 1.5(10+12)m (the mSq & 6 are multiplied)

now you have

R= 0.00000175 / 1500000000000m

do the division

R= 1.16

Get youself a scientific calculator & ask the lecturer to show how to use the EXP key with the -/+ key & the (bracket) keys for calcs involving indices.

The link will take you to a site showing the use of indices in mathmatics.
Indices

Stick with it I failed maths when I was at school so went to college aged 30 something with no formal maths grade & the best advice my old lecturer gave me was to get hold of some GCSE maths course/revision books from any bookshop & go through them.
Also get yourself these two books
Electrical Installation Calculations: v. 2 by A.J. Watkins and Russell K. Parton
Electrical Installation Calculations: v. 1 by A.J. Watkins and Russell K. Parton

Hope thats of some help to you.

J

Welcome along

P

#### Phil

welcome to the forum

#### Paul.M

##### -
welcome to the forum
This post is 3 years and 8 months old! Have you two been drinking :17:

#### brucelee

##### -
Hi and welcome to the forum

M

#### MarkieSparkie

Err, this is electrical forum archeology.:confused5: Hi, a belated welcome to the forum.

C

Hi and welcome

Mentor
Arms
welcome along

:welcome: