Now here's some

BASIC'S

It is sometimes useful to know some simple calculations. Say how big a fuse to fit in a certain
piece of equipment Etc. Well here goes!

OHMS LAW.
This a law that governs how electrical units are interrelated. The units concerned are. The OHM
a unit of resistance. Symbol "R". It's value is in ohm's believe it or not. The next is VOLTAGE
a unit of pressure. Symbol "V". Or volts. And the last is CURRENT this is the quantity of electrons
which are present in a circuit. Symbol "I" Or amps. And the relationship is

V = I X R ie, Voltage = current times resistance,it's as simple as that! And from that we can
deduce that,Current = Voltage divided by Resistance. And Resistance = Voltage divided by
current.
Or you could look at it this way

Let's look at a simple example. An electric fire resistance = 230 Ohms,and the applied voltage is
230 volts then the current in the circuit would be. (Voltage divided by Resistance) 1 Amp.
If we needed a fuse to protect this circuit what would we chose? This is were it becomes a little
tricky! A 1 Amp fuse might do,but this is not a PREFERRED VALUE so we would pick a 3 Ampfuse,as the preferred values of Mains type fuses are 3 Amp. 5 Amp and 13 Amp as you might know. I will include other examples in THEORY

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