
Two-Terminal Components
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4.4.4 Power Resistors
When choosing a resistor, it is wrong to consider only its “ohmic” value. The maxi-
mum power that it can dissipate without damage must also be considered. For the
standard resistors, typical power values that can be dissipated are 1/8 W, 1/4 W,
and 1/2 W.
This is generally dened as nominal power—the value of power that the resistor
can dissipate, when at room temperature of 25°C, without permanently altering its
structure. A power resistor is able to dissipate nominal powers equal to 1 W, 2 W
and more. Commonly, it has a parallelpiped shape (rather than cylindrical) and a
ceramic body. The resist ...