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.