2.2.4

Rheostat

14. Of the following resistors, which has a single fixed terminal and a shaft-driven, movable contact?

It maintains close tolerances in response to temperature changes.

15. The carbon film resistor has which of the following characteristics?

They have a negative temperature coefficient.

16. Thermistors possess which of the following qualities?

Filament resistance increases when the bulb is energized.

17. Which of the following statements best describes incandescent bulbs?

They produce twice the lumens per watt compared to incandescent lamps.

18. Which of the following statements best describes fluorescent lamps?

This represents an overload condition that will open the fuse.

19. A wire-wound resistor in a series circuit with a supply voltage of 45 VDC has a nominal value of 64 ohms. It develops a problem which results in it being 40% partially shorted. The circuit fuse is rated at 1 amp. Which of the following statements is correct?

Rated by maximum current the switch can pass when closed.

20. Which of the following describes the most important characteristic of how switches are rated?

All electrical tools should be tested on a regular schedule.

Of the following statements concerning electrical safety, which is correct?

Unidirectional limit switch

Of the following, which type of switch would normally be found at a terminal landing?

Double-pole, Double-throw, Normal Open switch

What does the designation DPDTNO switch represent?

3760 ohms

What is the minimum amount of resistance that would be found on a 4.7K ohm resistor with 20% tolerance?

Poles

Which of the following refer to the moveable contacts on a switch?

When the switch is actuated once, the contacts close and remain closed.

Which of the following statements best describes maintained-contact switch action?

Contact wear is always greater on DC swittches than AC switches.

Which of the following statements is correct regarding switches?