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Appendix
2
Resistors
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Resistance is measured in Ohms.
1k = 1000 W
1M = 1000000W |
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The Colour Code |
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The number of Ohms resistance is indicated by a series of
coloured bands on the resistor. |
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Start with the coloured band which is
nearest to the end of the resistor (in the
illustration above, the red band).
The first two bands tell us the first
two digits of the number of Ohms.
The third band tells us the number
of zeros which follow the first two digits.
So, in the example illustrated above,
the resistance is 2 (red), 7 (violet) followed by 4 zeros
(yellow). That is, 270k.
The last colour indicates the "tolerance" of the
manufacturing process. |
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Capacitors |
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The basic unit of capacitance is the
Farad. However, the Farad is a very large quantity of
capacitance. Usually capacitance is stated in pF (picoFarad),
nF (nanoFarad) or µF (microFarad).
On some capacitors, the colour code is
used but more often, the capacitance is written on the
component, in pF, nF or µF.
1µF = 0·000001 F = 10-6F
1nF = 0·000000001 F = 10-9F
1pF = 0·000000000001 F = 10-12F
Therefore, 1µF = 1000nF = 1000000pF |
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