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Important questions of dual nature of radiation and matter

Dual nature

Important questions of dual nature of radiation and matter

Dual nature

In this assignment, important questions of dual nature of radiation and matter , i am trying to provide some important questions based on the chapter dual nature of radiation and matter, student preparing for 12th board exam must solve all the questions , this chapter is little bit easier than other previous chapter of physics class 12th.Numerical based on this chapter is bit  easier than other chapters, so prepare this chapter nicely , and solve all the questions , i am sure that students will get benefit from this assignment of important questions of dual nature of radiation and matter.

Dual nature of matter and radiation

  1. List important observations made by Lenard which lead to quantum theory of radiations .
  2. State De-Broglie hypothesis . Derive an expression for the De-Broglie wavelength associated with an electron accelerated through a potential V . draw the schematic diagram  of a localized-wave describe the wave nature of the moving electron .
  3. Define the term threshold frequency and stopping potential in relation to the phenomenon of photoelectric effect . how is photoelectric current affected on increasing the (I) frequency (II) intensity of the incident radiations and why?
  4. Sketch the graphs showing the variation of stopping potential with frequency of incident radiations for two photosensitive radiations for two photosensitive materials A and B having threshold frequencies ѵ0 > ѵ0’ respectively . (I) which of the two metals ,A and B has higher work function ? (II) what information do you get from the slope of the  graphs ? (III) what does the value of the intercept of graph  A on the potential axis represent ?                                                                                                                 FOR IMPORTANT QUESTIONS OF RAY OPTICS -CLICK HERE
  5. Draw the graphs showing the variation of photoelectric current with anode potential of a photocell for (I) the same frequencies  but different intensities I1 >I2 >  I3 incident radiation, (II) the same intensities but different frequencies  ѵ1> ѵ2 >ѵ3 of incident radiation . Explain  why the saturation current is independent of the anode potential.
  6. What is the photoelectric current ? Write Einstein’s photoelectric equation and use it to explain (I) independence of photoelectrons from intensity , of incident light , (II) Existence of threshold frequency for emission of photoelectrons.                                                                                                 FOR IMPORTANT QUESTIONS OF WAVE OPTICS AND OPTICAL INSTRUMENT CLICK HERE
  7. An electron of mass m  and charge q is accelerated from rest through a potential difference V  , obtain the expression for the de-Broglie  wavelength  associated with it . if electron and proton are moving with the same K.E. , which one of them will have a large De-Broglie wavelength associated with it ? give reason .
  8. State the dependence of the work function on the K.E. of electrons emitted in a photocell . (a) if the intensity of the incident radiation increases to double of its initial intensity what change occur in the (I) stopping potential and (II)photoelectric current.(b) if the frequency of the incident radiation is doubled what change occur in the (I) stopping potential (II)photoelectric current(III) K.E. of the photo electron emitted
  9. Given below in the graph between frequency of the incident light and maximum kinetic energy of the emitted photoelectron find the value of (I) threshold frequency and (II) work function from the graph.

    dual pic-1
  10. In a photoelectric effect experiment , the graph between the stopping potential V and frequency v of the incident radiation on two different metal plate P and Q  in the fig. (I) which of the two metal plates , P and Q has greater value of work function ?(II)what does the  slope of the lines depict ?

    dual pic-2
  11. Ultraviolet light of wavelength 2271 A from a 100W mercury source is incident on a photocell made of molybdenum metal , if the stopping potential is 1.3 V , estimate the work function of the metal.

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