Home  Resources  References  Tubes  Forums  Links  Support  Sale  Search 

Back Next



    By using 50 to 150 commutator segments and armature conductors, the ripple can be very greatly diminished until it approaches very closely to pure D.C. The electromagnetic field which requires D.C. current for its supply, may now derive its voltage from the generator itself, instead of from an external battery or generator and as shown in Fig. 20, the field is connected in parallel with the armature or in shunt, as it is most usually referred to.
    Now that you have finished Lesson Three, lay down the text-book for a moment and review in your mind what you have read. Go over the lesson mentally as far as possible. Then take up the lesson again, and be sure you have not missed any of the important principles, particularly those which are most essential--they are the key to the whole lesson.

TEST QUESTIONS

    Number your Answer Sheet No. 3FR and add your Student Number.
    Never hold up one set of lesson answers until you have another set of lesson answers ready to send in. Send each lesson in by itself before you start on the next lesson.
    In that way we will be able to work together much more closely, you’ll get more out of your course, and better lesson service.
  1. State the difference between static and dynamic electricity.
  2. Explain the action of like and unlike charges.
  3. What are the two principal methods used to produce electric current ?
  4. A battery of three cells in series, each having an e.m.f. of 1.5 volts, what is the total voltage or e.m.f. of the battery ?
  5. Draw a diagram showing how three dry cells are connected in parallel.
  6. What is the most important thing to consider when connecting dry cells in various ways ?
  7. Explain briefly the difference between a primary cell and a secondary cell.
  8. What device is used to measure the specific gravity of an electrolyte ?
  9. Upon what principle does an electric generator operate ?
  10. Explain briefly the difference between a D.C. and an A.C. generator.


  Back 29 Next  


Content©1931, National Radio Institute
Webpage©1997, Nostalgia Air
Transcriber  Jennifer Ellis