Study help only, not test help.

Discussion in 'Homework Help' started by pfelectronicstech, Apr 13, 2012.

  1. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Ok, I have 2 weeks to study for a big test. They gave us study material with 40 questions just as a guideline. I want to enter some questions and for you guys to tell me if I'm right or wrong. Kind of an exercise for all of us.

    A modulation technique that uses two tones that are separated in frequency is] FSK/Frequency-shift keying transmission systems. Right or wrong?

    In order to recover audio from a received single sideband signal, the receiver must] reinsert the missing carrier. Right or wrong?

    What does a relaxation oscillator depend on for operation] Negative resistance. Right or wrong?

    In order for a circuit to oscillate, Its essential that the circuit have] regenerative feedback. Right or wrong?

    Thanks for any critiques.
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    The answers sound good to me. Are they multiple choice questions?
     
  3. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Yeah multiple choice, do you guys need the other choices? I'm surprise Electronics techs aren't having fun with this thread, testing their knowledge.
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,751
    4,797
    My guess is that the answers you've provided are the correct one, but it's possible that one of the other options was a better answer, so it would be good to post all of the options. For instance, if one of the other options for the first one was BFSK, then that is a better answer than FSK because it is more specific to the details given.
     
  5. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Ok, I'm gonna post some more questions today that I am having trouble with. I will post all the options and what I think it is. The second half of these questions are giving me some fits. Again thank you for the help.
     
  6. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    I included the circiut
    Which of the following statements about this circuit is correct?
    A. To obtain waveform 3 at the output of this circuit, both switch S1 and switch S3 would have to be
    closed.
    B. To obtain waveform 3 at the output of this circuit, either switch S1 or switch S3 must be closed.
    C. To obtain waveform 3 at the output of this circuit, only switch S2 must be closed.
    D. No combination of closed switches will produce waveform 3 at the output of this circuit.

    My answer is D, correct?
     
  7. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Same circuit is used for this question.
    Look at the circuit diagram and the four waveforms that are shown in Figure A-5. Which of the
    following waveforms will be produced when only S1 is closed?
    A. Waveform 1 C. Waveform 3
    B. Waveform 2 D. Waveform 4

    My answer is A, correct or not?
     
  8. WBahn

    Moderator

    Mar 31, 2012
    17,751
    4,797
    Assuming these are ideal 5.6V Zener diodes, your answers are correct.

    Now, if you haven't already, sketch the output voltage for each of the eight possible switch configurations.

    Next, what is the simplest circuit mod you can think of to get Waveform 3?
     
  9. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Thanks for the help, I'm gonna list 3 or 4 more that are giving me fits in a little bit. Thanks again for all the help.
     
  10. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Here are two more, thanks for any help.

    Two electronics technicians are discussing the resistance of copper wire. Technician A says that the resistance
    of a copper wire decreases as its cross-sectional area increases. Technician B says that the resistance
    of a copper wire decreases as its length increases. Which of the following statements is correct?
    A. Only Technician A is correct. C. Both of the technicians are correct.
    B. Only Technician B is correct. D. Neither of the two technicians is correct.

    I say its C, both technicians are correct. Right or wrong?

    A digital bathroom scale is an example of an application where a strain gage might be used. In this device,
    the weight on the scale is the stress, and the deformation of the gage is the
    A. strain. C. pressure.
    B. force. D. potential.

    My answer is A. Strain. Right or wrong?
     
  11. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    Your first answer is wrong.
    A is correct in the second question. However, weight causes stress, but it isn't stress.
     
    pfelectronicstech likes this.
  12. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Thanks, its Technician B only right?
     
  13. WBahn

    Moderator

    Mar 31, 2012
    17,751
    4,797
    Sanity check time: Would you really expect the resistance of a one foot length of wire to be more than the resistance of a length of the same wire that went from New York to San Francisco?

    Or consider it this way: I have 100 ten-foot lengths of copper that, for argument's sake, each have 1 ohm of resistance. If I put these hundred copper wire resistors together in series to get a single thousand-foot copper wire resistor, would I expect to get more, or less, than 1 ohm of resistance?

    Now imagine taking all of these ten-foot long copper wire resistors and putting them together in parallel side by side to get a single ten-foot resistor (that was looking a lot like a much larger diameter wire). Would I expect to get more, or less, than 1 ohm of resistance.

    Your answer to the second question is correct.
     
    Last edited: Apr 15, 2012
    pfelectronicstech likes this.
  14. mlog

    Member

    Feb 11, 2012
    276
    36
    You have the stress-strain question correct, but why do you think Technician B is correct?
     
  15. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Here is another question that I think I'm right on.

    Two electronics technicians are discussing the procedure that’s used to measure resistance in a circuit.
    Technician A says that to ensure an accurate reading, it’s important to start with the meter set to the highest
    resistance range and then decrease the range as necessary. Technician B says that to ensure an
    accurate reading, all power to the circuit must be turned off. Which of the following statements is correct?
    A. Only Technician A is correct. C. Both of the technicians are correct.
    B. Only Technician B is correct. D. Neither of the two technicians is correct.

    I believe its C. Both techs are right because I believe you do have to disconnect the power for shock reasons and prevent damage to equipment. Plus you set the multimeter to the highest setting then step it down to prevent damage to the multimeter. Am I correct?
     
  16. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Yes, when measuring in a "circuit" that would be important as low resistace ranges on the meter might cause too much current through unknown components in the circuit. That's definitely true.

    That's definitely true as well, the "circuit" whatever it is might have voltages that will damage the tester and/or cause erratic resistance readings.
     
    pfelectronicstech likes this.
  17. WBahn

    Moderator

    Mar 31, 2012
    17,751
    4,797
    Don't answer questions that weren't asked. The question ONLY asks about obtaining the most accurate reading; it's not asking anything about the safest reading or the reading least likely to damage something.
     
    pfelectronicstech likes this.
  18. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    OK I'm confused now, I was set on Both techs A and B. Are you saying its B only? I hate these types of questions, I always end up screwing them up, and answering parts of the question that wasn't asked.
     
  19. pfelectronicstech

    Thread Starter Member

    Jan 18, 2012
    178
    4
    Here is another set of questions, see if I'm right? Illustration included.

    Look at the four schematic symbols shown in Figure A-4. All four of these devices
    A. conduct current in only one direction. C. are used as replacements for relays.
    B. are designed to operate in AC circuits only. D. exhibit negative resistance.

    My answer is D. exhibit negative resistance. That answer was by process of elimination.

    Thanks again for the help.
     
  20. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Yes - are you confident in identifying each device type & convinced that each can exhibit negative resistance?
     
    pfelectronicstech likes this.
Loading...