Test your basic knowledge |

Subjects : science, engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. A transformer with 3000 turns in the primary winding has a primary voltage of 4 -800 volts and a secondary voltage of 240 volts. How many turns are in the secondary winding?






2. The standard frequency of power supplied by the power company is...






3. The purpose of a zig-zag transformer is to...






4. Alternating current may be defined as...






5. The primary function of a power transformer is to provide...






6. If a voltmeter were placed between two phase leads of a three-phase 480-volt system - the meter would read...






7. The standard frequency of alternating current used at a mine is...






8. What happens to a motor that is connected to a three-phase cable when two of the cable's leads are reversed?






9. Current that changes periodically in direction is...






10. At what rate should mouth-to-mouth resuscitation be applied?






11. A transformer has 2000 turns in the primary and 500 turns in the secondary. The primary voltage is 3 -200 volts. What is the secondary voltage?






12. Compared to the secondary of a loaded - step-down transformer - the primary has...






13. The load to which the secondary winding of a current transformer was connected has opened. The secondary leads should be...






14. A current transformer has a ratio of 350:5. If the phase current is 70 amperes - what would be the secondary current?






15. A burn causing a blister is classified as a...






16. Current transformers - or CT's - are used to...






17. The size of a transformer is measured in...






18. All transformers step voltage up or down by...






19. Operating coils - motors - transformers - relays and solenoids depend upon...






20. What is the first step to be followed in aiding a victim of electrical shock?






21. If current were flowing through a grounding resistor in a 440-volt - resistance-grounded system - this would probably be because...






22. A control power transformer...






23. Not true about AC power?






24. The neutral ground-bed electrical power system of an underground mine should be separated from the lightning arrestor grounds by at least...






25. The minimum allowable size for trailing cables for mobile haulage equipment powered by alternating current is...






26. Find the turns ratio of a single-phase transformer with the following values: Primary power of 5KW - secondary current of 100 amps - and primary voltage of 250 volts.






27. If any two-phase wires are reversed on a three-phase motor - the motor will...






28. The primary leads of a single-phase transformer should be connected to the...






29. Which of the following does a squirrel cage induction motor have?






30. Two 10-hp induction motors are operating on 460 volts AC. One motor is connected by single- phase; the other is connected in three-phase. The three-phase will...






31. What position of a selector switch using a voltmeter would you select to check a 120-volt AC circuit to obtain the most accurate reading?






32. A solenoid coil is...






33. 460 volts AC is required to operate two motors - one connected in single-phase and the other connected in three-phase. The three-phase motor will...






34. The property of an electrical circuit that opposes any change in voltage is called...






35. When connecting 3 single-phase transformers into a three-phase system - which of the following is NOT required for the single-phase transformers.






36. If a voltmeter is connected between a phase lead and the ground of a three-phase 480-volt system - the meter will read...






37. If 2000 watts is read in the primary of a single-phase transformer - What is the wattage in the secondary? (Assuming no losses.)






38. The secondary windings on a 10:1 step-down transformer will have a wire size...






39. The following motor leads are brought out of a 3-phase motor (T1 - T2 - T3 - T4 - T5 - T6). This motor is probably for...






40. A transformer has a primary voltage of 2 -400 volts and a secondary reading of 120 volts. If there are 1 -500 turns on the primary - how many turns are on the secondary?






41. How should clothing be removed from a burn?






42. A transformer with a 1:1 ratio is usually a (an)...






43. Surface transformer installations - unless constructed to eliminate shock hazards - must be installed at least...






44. A 3-phase - 2 speed - constant torque motor is running at fast speed. The motor windings are connected wye for fast speed. Motor leads T4 - T5 and T6 are connected to the line leads. Motor leads T1 - T2 and T3 should be...






45. Current in an AC circuit may be measured by...






46. What is the danger when working around capacitors?






47. AC voltage is raised or lowered by means of...






48. How can you tell if a victim receiving mouth-to-mouth resuscitation is getting air into the lungs?






49. If 13 -200 volts are measured from phase-to-phase across a wye-connected secondary - What is the phase-to-ground voltage?






50. Define alternating current...