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On the boards
In practice, you might find that your resistor’s measurement isn’t
exactly 10 k. It may be, say, 9.5 k or 10.5 k. This is due, of course, to
tolerance. Both the resistor and the multi-meter have a tolerance:
indicated on the resistor by the last coloured band: the multimeter’s
is probably around ± 5%. Chances are, though, you’ll
find the multi-meter reading is as close to 10 k as makes no
difference.
Now you’ve seen how your multi-meter works, you can use it
to measure any other resistors you have, if you wish. You’ll
find that lower value resistors need to be measured with the
range switch on lower ranges, say Ω x 100. Remember — if
you have an analogue multi-meter — every time you intend
to make a measurement you must first zero the multi-meter.
The process may seem a bit long-winded for the first two or
three measurements, but after that you’ll get the hang of it.
The second circuit
Figure 2.4 shows the next circuit we’re going to look at
and how to build it on breadboard. It’s really just another
simple circuit, this time consisting of two resistors in a line
— we say they’re in series. The aim of this experiment is to
measure the overall resistance of the series resistors and
see if we can devise a formula which allows us to calculate
other series resistors’ overall resistances without the need
of measurement.
Figure 2.5 shows the more usual way of representing a circuit
in a drawing — the circuit diagram. What we have done is
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