The atomic structure of a material is the greatest factor in determining its resistance.
Correct. That is the first and probably the most important of the four factors that determine the resistance
of a material. But let's not underrate the other three. For instance, the next factor is the length of the conductor.
It just stands to reason that if a conductor one foot long has a certain amount of resistance, then a conductor made
of the same material but two feet long would have more resistance. In other words, the longer the conductor, the
more resistance it offers to current flow. The next factor is the cross-sectional area of the conductor (don't be
confused by the big words, we simply mean how big around it is) works the opposite way. A conductor one foot
long and 1/4 inch in diameter has a certain resistance. A conductor made of the same material, one foot long but
1/2 inch in diameter, would have less resistance. Just like a water pipe. It's harder to get the same volume of
water through two pipes when one pipe is smaller than the other. OK? Now answer the following question:
A conductor four inches long and one inch in diameter has a resistance of 8 ohms. If we were to stretch
this conductor to eight inches, with the diameter decreasing to one-half inch, the resistance would
stay the same.
Wrong. We just said that resistors may be small in size-- 1 inch in length and 1/4 inch in diameter, yet
range in resistance from less than one ohm to more than several million ohms. The physical size of a resistor has
a lot to do with the power rating (which we'll go into later), but practically nothing to do with the amount of
resistance. Go back to Page 1-7A and choose the correct answer.