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Newnes Circuit Calculations Pocket Book
book

Newnes Circuit Calculations Pocket Book

by Thomas J. Davies
April 2016
Intermediate to advanced content levelIntermediate to advanced
384 pages
12h 56m
English
Newnes
Content preview from Newnes Circuit Calculations Pocket Book
d.c. circuits 29
1 kilowatt-hour (kWh) = 1000 watts x 60 minutes
x 60 seconds
= 3 600 000 joules, or 3.6 x 10
6
J
P which equals VI, can be expressed in two other ways.
Since
V = IR
then
P = IRI = I
2
R
Since
V
I = -
R
then
V V
2
p=V- =
R R
The main units used are
1 The watt (W)
2 The megawatt (MW) = 10
6
W
3 The kilowatt (kW) where 1 kW = 10
3
W
4 The milliwatt (mW) where
1
mW = 1/10
3
W =
10
~
3
W
5 The microwatt (u.W) where 1 fiW = 1/10
6
W = 10"
6
W
It therefore follows that 1 MW = 10
3
kW. The relationships
between the subunits are the same as those for voltages, covered in
Chapter 1, and for current, covered in Section 3.2.
3.5 Types of circuit ...
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Publisher Resources

ISBN: 9781483101132