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

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  1.  
    2. SIR WILL PHOTO CURRENT EXISTS IF THE APPLIED POTENTIAL IS GREATER THAN STOPPING POTENTIAL?? IF IT IS TRUE EXPLAIN IT..
    2 years ago by ABHINAV

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  2.  
    3. Sir what is the difference between electrons and photoelectrons?
    3 years ago by Naman Kumar

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  3.  
    4. Sir, At 2:18 min, you said at higher frequency, at zero voltage current will be more. How? current is independent on the frequency of the light
    4 years ago by Anirudh Saripalli

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  4.  
    5. sir when potential difference increase then velocity of electron increases so q/t increases so current should be increased but why not
    5 years ago by Ujjwal Kar

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  5.  
    6. Sir but u have already supplied the required energy hv> work function so all electrons should come out?
    5 years ago by Anuj Sawhney

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  6.  
    7. sir if only velocity is increasing after vp and not the current then photon flux must be time independent....
    5 years ago by Abhishek Rana

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  7.  
    8. Sir, the notes which I'm making through your video lectures are these notes helpful in CBSE boards preparation?
    5 years ago by Aditya Ojha

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  8.  
    9. It was not discover by Albert it was explained by him
    5 years ago by Nikhil Chaturvedi

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  9.  
    10. Photoelectric effect was not discovered by Einstein .it was discovered by Herz and explain by Einstein
    5 years ago by Babulal Prasad

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  10.  
    11. sir why we can not consider the momentum of photon
    5 years ago by vikas agrawal

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  11.  
    12. If we decrease wavelength more than the threshold wavelength, does the speed of electron escaping out changes.If it does then why?
    6 years ago by Shrikrishna Namdeo
    Ans 1 ->
    Yes,if we decrease the wavelength even more than the threshold wavelength the electron speed increases because of the increase in the energy of the incident photons as we decrease the wavelength the frequency increases thereby increasing the energy of the incident light. hope it helps.
    6 years ago by Zac Zayn

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  12.  
    13. is the straight part linear? and why is there any resisitance offered by the circuit if so then where
    6 years ago by Vansh Mishra

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  13.  
    14. sir v=0 means there is no potential diff. between the electrodes so when the electron cloud comes out then the electrode must have now been on a higher potential and so when v=0 then i=0 pls help me out sir
    6 years ago by Vansh Mishra
    Ans 1 ->
    No,when v=0,i is not equal to zero in the beginning because of the the incident photons on the metal plate which caused the electron flow and thereby constituting current in the circuit initially even without the application of voltage.
    6 years ago by Zac Zayn

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  14.  
    15. sir i have 2 doubts first of all why is it disobeying ohm's law and second that as we inc. the potential after the pinchoff potential the speed of electrons also inc.s and so the rate of flow of charge should also inc. so why is the current const.??
    6 years ago by Vansh Mishra
    Ans 1 ->
    1.(Ohms law cannot be applied to discharge tubes)and 2.(because the current doesnot depend upon the speed of electrons but rather on the n.o of electrons,even though the speed of electrons increase but the electron flux remains the same because the electron flux depends on the incident photons on the metal plate,as long as the photon flux is constant the electron flux is constant and hence the current remains constant irrespective of the increase of voltage and electron speed) hope it helps.
    6 years ago by Zac Zayn

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  15.  
    16. is it possible that 1 electron absorbs enough energy for example 3 times the threshold frequency and collides with another electron and transfers some of its energy to other electron which is more than the threshold energy and both the electrons are ejected?
    7 years ago by Aditya
    Ans 1 ->
    depends upon the work function of the metal. but if we consider your case we might contradict the second condition which states that each photon can at the most eject one electron. nice question btw.
    6 years ago by ABHISHEK SHANKAR
    Ans 2 ->
    but yes as sir said we consider that no time lag exists so the electrons will be ejected out almost instantaneously without colliding with other electrons
    6 years ago by ABHISHEK SHANKAR

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  16.  
    17. The surface of Lithium of work function ? is illuminated by electromagnetic radiation whose electric field component varies with time as E=a(1+Cos?t)Coskt . The maximum kinetic energy of photo electron liberated from surface is______________
    7 years ago by srikar malyala
    Ans 1 ->
    seperate the terms of E equation use trignometry..wwe will get two light waveswhich have maximum frequency .select that wave for calculating ke max use that frequency
    7 years ago by Apoorva Gupta

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  17.  
    18. Sir on increasing the frequency velocity of electrons incerased so current flow should also be increased as number of charge passing per unit time increases?
    9 years ago by sudeep khare

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  18.  
    19. How can be derive the formula of impulse due to fast electron?
    9 years ago by sudeep khare

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  19.  
    20. Two particles of same mass moving in mutually perpendicular directions and have debroglies wave length lambda 1 and lambda 2 with respect to initial frame of reference.Find the debroglies wave length of each particle with respect to centre of masss.
    9 years ago by mukhtar
    Ans 1 ->
    You can first find the momentum of each particle using p =h/(lambda) and then their speeds v1 and v2 by using p/m.... now calculate the velocity of centre of mass of the two particles using relation v(cm)=(m1v1 i +m2v2 j)/(m1 + m2) now calculate the relative velocity of each particle in frame of their cm using v1-v(cm) and v2 - v(cm) now calculate debroglie wavelength in frame of cm as lambda = h/mv(rel)
    9 years ago by Physics Galaxy

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  20.  
    21. in experimental study of Photo Electric Effect, why is electron cloud formed.
    10 years ago by Kshitiz agrawal
    Ans 1 ->
    When potential difference across the tube is low anode potential is not able to pull all electrons ejected from cathode at the same rate so excess electrons collect outside the cathode and repel other ejecting electrons which causes electron cloud to be developed...
    9 years ago by Physics Galaxy

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