Principles & Applications Electricity Principles & Applications Sixth Edition Richard J. Fowler Chapter 4 Circuit Components ©2003 Glencoe/McGraw-Hill

INTRODUCTION Cell Characteristics Testing Lamps Resistor Color Codes Types of Switches Testing Fuses

Cell Characteristics Volts 2.8 Lithium 1.5 Silver oxide 1.25 Nickel-cadmium Alkaline- manganese dioxide Carbon-zinc 0 50 100 % of discharge

Testing a Lamp When the lamp is not blown, its resistance <1kW µW When the lamp is not blown, its resistance will be less than one kilohm. When the lamp is blown (open), its resistance will be infinite.

Neon Lamp The next slide shows how a neon lamp responds to dc, then to ac, and then again to dc.

Click on the image to run the display. To rerun the display, click again on the image.

Operation of a Flasher Lamp Just click the mouse one time and watch the action! Cell OFF ON

Operation of a Flasher Lamp Cell ON OFF The flashing will discontinue when the lamp is turned off.

Exploding Neon Lamp The next slide shows what can happen to a neon lamp when the current limiting resistor shorts out.

Click on the image to run the display. To rerun the display, click again on the image.

Cell and Lamp Quiz The ____ cell has the most output voltage. lithium The ____ cell has the least output voltage. nickel-cadmium The ____ cell’s voltage drops most rapidly when it is discharging. carbon-zinc The nominal voltage of the alkaline- manganese dioxide cell is ____ volts. 1.5 A blown lamp has a(n) ____ resistance. infinite

Resistor Color Codes Yellow 4 7 Violet 00 Red ±10 % Silver

Resistor Color Codes 56 x 103 ± 5 % = 56000 ± 5 % = 56 kW ± 5 % Green = 5 Blue = 6 Orange = 3 Gold = ± 5 % 56 x 103 ± 5 % = 56000 ± 5 % = 56 kW ± 5 %

Resistor Color Codes = 464 kW ± 2% 4 6 4 0 0 0 ± 2%

Overheated Resistor The next slide shows what can happen when the power rating of the wire-wound resistor shown below is greatly exceeded.

Burning Resistor Click on the image to run the display. To rerun the display, click again on the image.

Toggle Switches Single-pole, single-throw (SPST) Single-pole, double-throw (SPDT) Double-pole, single-throw (DPST) Double-pole, double-throw (DPDT)

Rotary Switches OR OR Single-pole, three-position (SP3P) Double-pole, three-position (DP3P)

Make-Before-Break (Shorting) Switch In position 1

Make-Before-Break (Shorting) Switch In transition from position 1 to position 2

Make-Before-Break (Shorting) Switch In position 2

Testing a Fuse When the fuse is not blown, its resistance will be less than one ohm. When the fuse is blown (open), its resistance will be infinite.

Slow-Blow Fuse This material connects the fuse element sections together. When the over-current is small, the alloy slowly softens and weakens. Then the spring pulls the element sections apart. Spring When the over-current is extremely large, this section immediately burns open.

Blown Fuse (1st case) This slow-blow fuse was blown by a very large over-current. Notice that the spring is still in place.

Blown Fuse (2nd case) This slow-blow fuse was blown by a small over-current. Notice that the spring has retracted a section of the fuse element.

Slow-Blow Fuse in Action Watch the alloy melt and the spring retract. Click on the image to run the display. To rerun the display, click again on the image.

Resistor, Switch and Fuse Quiz A resistor with yellow, violet, red, and gold bands has a resistance of ____ kilohms. 4.7 ± 5% A resistor with red, red, red, red, and red bands has a resistance of ____ kilohms. 22.2 ± 2% The ____ switch can provide the most switching functions. rotary The ____ switch can be either a shorting or a non-shorting switch. rotary A fuse with infinite resistance is a ____ fuse. blown

REVIEW Cell Characteristics Testing Lamps Resistor Color Codes Types of Switches Testing Fuses