Robot Building for Beginners, Third Edition

(Marvins-Underground-K-12) #1

CHAPTER 9 ■ RESISTORS


It may be worth buying a cutter from a local store rather than from a catalog (see Table 9-2), so that you
can experience how a particular model feels in your hand.


Resistance and Ohms


The unit associated with resistance is ohms. This is abbreviated with the symbol W. So, 100 ohms is the same
as 100 W. There isn’t any difference.
It doesn’t matter if you understand or have a feel for ohms yet. Recall that resistance is like the smaller
pipe sizes and tiny holes in your showerhead. A larger ohm number represents larger resistance, which is
sort of like a narrower pipe.
Most electronic parts can’t take the full force of the battery. They need something to reduce the flow;
that’s what resistors do.


Figure 9-5. Flush wire cutter or nippy cutter


Table 9-2. Wire Cutters


Supplier Part Number Price


All Electronics FC-14 $4.50


Electronix Express 0602MS01 $6.00


Jameco 159274 $4.95


Jameco 146712 $8.95


Micro-Mark 80333 $14.25


SparkFun TOL-08794 $1.95

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