Resistance and Neon Lamp

  1. Dear we have been asked to devise an experiment to find the resistance of a resistor using neon lamp. Can some help me please i have to submit it in next couple of days. I know about resistance but have no idea of neon lamp. Please help me making lab report.
     
  2. jcsd
  3. berkeman

    Staff: Mentor

    That's a tough one. You will need to look up the voltage and current characteristics of neon lamps to start this. You could check the wikipedia.org article as a starting place. Once you have that, you should be able to figure out a way to use a variable voltage source and the neon bulb to give you a way to estimate the resistance of the resistor.

    Tell us what you learn about the neon bulb, and what your initial thoughts are for how to use it.
     
  4. Now sir neon lamp is what we have been told by friends that its a type of bulb which glows at any particular value of voltage. The lamp shown in the figure glows only when the voltage drops from the positive half to zero in that quarter of cycle the bulb glows. Please tell mew that the how to calculate the time between two glows theoretically.what is the formula and how to link the resistance with that time?
     

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  5. berkeman

    Staff: Mentor

    Ah. Is that a diode in the upper left part of the circuit? It just sounds like you are to use some RC time constant or RC impedance characteristic to help you figure out the R value, based on knowing the C value and having control over the AC source.

    We don't do your work for you. What can you do with the AC source and value of the capacitor to start to tell you the value of R?
     
  6. Sir will we use the formulas q =Q (1-e-t/RC) ? and time and resistance are directly proportional because time period=RC?
     
  7. berkeman

    Staff: Mentor

    I think either that equation or a similar one. How are you thinking of running the circuit to let you see the time constant?
     
  8. Sir please tell me which equation i should use for theoretical value of resistance if we have given C, time period?
     
  9. berkeman

    Staff: Mentor

    I don't know. You still haven't answered my question about the diode-like thing, and you haven't said anything about the voltage source's capabilities. You need to do the thinking about how you can do something with this circuit to give you a visible indicator or time constant that you can relate the to value of the resistor.
     
  10. Sir that is a diode, and voltage source is any mains supply.
     
  11. berkeman

    Staff: Mentor

    Then you should be looking at the turn-on characteristics of the neon lamp that you will use. What is its fire voltage? What is its sustain voltage? What currents are required for fire and sustain?
     
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