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High School/JEE/NEET/IPhO Physics | 17-19 Yrs

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  1.  
  2. Where can i get the SAPI Caps for this chapter and whhole Optics ??
    2 years ago by Sahil Madaan

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  3.  
  4. sir where will we find the solutions of the quset questions because i want to correct the questions which i did wrong or was unable to do that
    3 years ago by

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  5.  
  6. Sir you have told in this video that photodiode is used in forward bias but ncert says(page no. 487) that photo diodes are preferably used in the reverse bias condition. Not only this ncert has even asked a question also(Solved Example 14.6, page no. 487) , which is as follows - The current in the forward bias is known to be more than the current in the reverse bias. What is the reason then to operate the photodiodes in reverse bias? And there is a well explained answer for this on the same page of ncert.
    4 years ago by
    Ans 1 ->
    -Hemant Jakhar
    4 years ago by
    Ans 2 ->
    Moreover, if we follow the mechanism mentioned in ncert and apply it in forward bias condition....it seems that the current in forward bias condition should decrease instead of increasing. Although that decrease in current will of order of micro ampere while current in forward bias is of order of milli ampere. So I think it will be very hard to detect it in forward bias graph scale. Sir , please clarify... -Hemant Jakhar
    4 years ago by
    Ans 3 ->
    In other words (i.e. in words of explanation for the above question on page 487-488 of ncert), it can be inferred that fractional change in reverse bias condition will much greater (and will be positive),as it is evident that reverse bias current is increasing with increase in incident light ray intensity. And furthermore from that explanation(in ncert) I have speculated that in case of forward bias, fractional change in forward bias current will be negative and very very small in magnitude. Sir pls check and correct me if I am wrong. Yours , Sincerely -Hemant Jakhar A small physics teacher in CLC sikar. By the way Sir, I am great fan of yours. Your are such great teacher and teach with such a clarity. Thank you for providing with such beautiful physics video lectures.
    4 years ago by

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  7.  
  8. sir what are minority carriers in reversed biasing
    4 years ago by Vishwas Sharma

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  9.  
  10. sir if the sc is heavily doped .. e field should increase.. so please justify the difference between zener breakdown and avalance breakdown...
    5 years ago by Abhishek Rana

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  11.  
  12. respected sir, when we short circuit the forward biased diode what happens to the 0.7 volt(or greater) potential drop across it? where have we accounted for it in the kirchoff loop law?
    5 years ago by vector addition
    Ans 1 ->
    sorry i got my answer the potential drop is 0 across an ideal forward biased diode
    5 years ago by vector addition

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  13.  
  14. doing great work sir
    5 years ago by Sarju Panchal

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  15.  
  16. in reverse biasing ef is towards left then why are holes and electrons not moving towards depletion layer???
    6 years ago by ishita goyal
    Ans 1 ->
    sorry i got it
    6 years ago by ishita goyal

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  17.  
  18. Is the electric field in depletion layer is from n to p or p to n? Which direction right to left or left to right?
    6 years ago by mukesh kumar sattavan
    Ans 1 ->
    n to p... that's how the depletion layer thickness increases? and junction potential increases
    6 years ago by ABHISHEK SHANKAR

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  19.  
  20. Sir, you have explained the working of a photodiode when the light sensitive junction diode is made to absorb the incident light....But the NCERT book has considered the junction diodeto be connected in reverse bias and it also states that reverse bias connection is preferred over the forward bias connection....Sir, I did not understand the reason for the above statement of the NCERT.... Hope you will clear address to my query.... Thank you sir.
    6 years ago by

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  21.  
  22. You cant make a PN junction with an intrinsic semiconductor..right?
    6 years ago by Chirayu Betkekar

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  23.  
  24. being depletion layer free from charge carriers and consist of only donaor ions on N type and acceptor ions on Ptype side, how electron hole pair generate in depletion layer on incidenting the photon on junction
    6 years ago by M NAGARAJU

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  25.  
  26. Sir how to get notes?
    7 years ago by Sudarshana Ghosh
    Ans 1 ->
    take screen shot of every page or write parallel to sir
    7 years ago by dinesh sai

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  27.  
  28. Why electric field is produced at interphase ?
    8 years ago by Ashish Sharma
    Ans 1 ->
    due to charges of positive and negative ions on the two sides of junction...
    8 years ago by Physics Galaxy

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  29.  
  30. Sir you are mentioning Al ( Pentavalent Impurity ) belongs Fifth Group but it actually belongs to 15th group . Am i Right ?
    8 years ago by Ashish Sharma
    Ans 1 ->
    Sorry I meant 13th Group not 15th .
    8 years ago by Ashish Sharma
    Ans 2 ->
    Al is not pentavalent, it is trivalent. Yes it belongs to group 13/3A.
    7 years ago by Manan Jhaveri

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  31.  
  32. The current flow in from resistance during positive half cycle should divide equally in D2 and D3...and same should be happened during negetive half cycle.Is their any effect on output emf and current due to this?
    9 years ago by sudeep khare

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  33.  
  34. Is bridge rectifier requires greater A.C. emf for rectification due to two diodes connected in series
    9 years ago by sudeep khare

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  35.  
  36. Why we use load resistance in rectifier?
    9 years ago by sudeep khare

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  37.  
  38. Can we use step up transformer in rectifier?
    9 years ago by sudeep khare

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  39.  
  40. what is the significance transformer in rectifier? why we do not connect the ac source directly?
    9 years ago by sudeep khare

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  41.  
  42. How zener diode can maintain same potential difference in it if Vext is greater than Vz?
    9 years ago by sudeep khare
    Ans 1 ->
    the potential difference across the load remains the same as Vz... the potential difference across the zener diode will change as the Vext is variable... so the excess current due to high electric field created by the V ext will always pass through the zener and will allow only that much current Ir to flow through the load thus maintaining the voltage? across the load
    6 years ago by ABHISHEK SHANKAR
    Ans 2 ->
    the voltage? across the load will be Ir. R and that will be equal to Vz
    6 years ago by ABHISHEK SHANKAR

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  43.  
  44. Respected sir I thinks resistance for reverse biasing should be inversely proportional to thickness of depletion layer because greater electric field cause easier for breakdown of pn junction?
    9 years ago by sudeep khare
    Ans 1 ->
    usually, the external potential difference in PN junction does not exceed the breakdown voltage in reverse bias as it is not designed for that
    6 years ago by ABHISHEK SHANKAR

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  45.  
  46. Respected sir can we use pn junction as a source of battery? if we join p side with n side through connecting wires then due to potential difference between them current we flow from p to n side. after sometimes when sufficient amount of electrons and holes are accumulated in p type and n tyoe which nullify the electric field in depletion layer then again the initial condition will arrive. After this again it form a depletion layer by diffusion of electrons and holes(which acts as self charging of battery). Then we can again use it by completing the circuit.
    9 years ago by sudeep khare
    Ans 1 ->
    basically it is just a conductor. so conductor cannot generate electricity. Do we get current by just joining copper wire. further the potential is developed across depletion layer so what you thought might be wrong.
    7 years ago by dinesh sai

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  47.  
  48. Why one p-type and one n-type semiconductor cannot be joint to form pn junction?
    9 years ago by sudeep khare

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  49.  
  50. sir i have read in ncert that photo diode is operated under reverse bias but here its under forward bias how?
    9 years ago by kartik sharma

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  51.  
  52. why current is not flowing when piont A become -ive and point B become +ive ?
    9 years ago by Gaurav Muliya
    Ans 1 ->
    Because diode becomes reverse biased...
    9 years ago by Physics Galaxy

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  53.  
  54. sir is the voltage we are getting in full wave rectifier different from the voltage without the centre tap since we have divided the voltage into two halves ... during the operation that mean we are getting low current for a particular half wave as compared half wave rectifier in operation ...?
    9 years ago by gursewak
    Ans 1 ->
    yes... due to centre tap.. voltage is reduced to half...
    9 years ago by Physics Galaxy

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  55.  
  56. sir why you put negative sign for current amplitude in full wave rectifier for second half cycle since you got all ur amplitude in the first quadrant
    9 years ago by gursewak
    Ans 1 ->
    it is for second half cycle as Im sin(omega t) will give current cycle below time axis ie -ve.... as it represents the output waveform from full wave rectifier correctly...
    9 years ago by Physics Galaxy

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  57.  
  58. Sir, in the animation direction of electron flow is shown same as that of current. Is that right?
    10 years ago by Shuchita Singh
    Ans 1 ->
    well, i got my answer, its not electron flow (e), its current flow (E).
    10 years ago by Shuchita Singh

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