Electricity & Electronic Workbooks

DC Fundamentals Unit 3 – Electronic Quantities

Exercise 3 – Circuit Resistance.................................................................................................

EXERCISE OBJECTIVE

When you have completed this exercise, you will be able to describe and measure resistance by
using a simple circuit. You will verify your results with a multimeter.

DISCUSSION

• The amount of voltage needed to cause current flow through a conductor varies with the
  physical and electrical properties of the conductor.


• The property of the conductor that resists the flow of current is called resistance.


• The unit of measure for resistance is the ohm (Ω).


• One ohm of resistance is present in a conductor when one ampere of current flows under one
  volt of potential difference.


• Resistors are devices designed to insert a specified amount of resistance into a circuit. There
  are four common types of fixed resistors: carbon composite, deposited carbon film, deposited
  metal film, and wire wound.


• Color bands are used to code the value of resistors.


• Conductance has a reciprocal relationship with resistance and measures the lack of
  resistance.


• The unit of measure for conductance is the siemen (S).


• The physical size of a resistor determines how much current can flow through it because
  current flow generates friction that causes heat.


• The watt is a measure of power.


• The physical size of a resistor is a measure of how many watts of power it can dissipate in
  the form of heat.