# Dual Nature of Radiation & Matter - Important Questions & Preparation Tips

In this article you will get the clue that from where and how the questions are being framed from chapter Dual Nature of Radiation & Matter

Created On: Nov 13, 2013 13:10 IST

CBSE Class 12th Chapter, Dual Nature of Radiation & Matter obtains 04 Marks. Experts of Jagranjosh.com offer the best practice material that covers all important questions so that students will not miss any portion while preparing for board exams or competitive exams. Consider the mentioned terms/questions at the time of studying.

Dual Nature of Radiation & Matter

• Basic principle for Millikan’s method for the determination of electronic charge.
• Why is metal piece heated when cathode rays strike against it?
• Why do gases become conductor at low pressure?
• What is quantization of charges?

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• Draw a graph between the frequency of light used for photoelectric effect and maximum kinetic energy of the emitted photoelectrons. Explain:

i.What does the slope of the graph represent?

ii. How is the work function of the metal surface obtained by the graph?

iii. What will be the effect on the nature of graph if the intensity of the incident light be doubled, or metal of lower work function be taken?

• Explain work function and threshold frequency in photoelectric effect. Give Einstein’s equation for photoelectric emission. What do the symbols stand for?
• Differentiate between thermionic emission & photoelectric emission?

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• Explain the meaning of photoelectric work function of a metal. How does its value affect the kinetic energy of liberated photoelectrons?
• What is the threshold wavelength in photoelectric effect?
• The work function of aluminum is 4.2eV. If two photons, each of energy 2.5eV are incident on aluminum surface, will photoelectric emission occur?
• Every metal has a definite work function. Even then, when light of single frequency is incident on metal, photoelectrons having different energies emitted. Why?

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• 5% energy of monochromatic light source is converted into light of wavelength 5600Å. If the power of the source be100 W, then how many photons light will be emitted by it per second?
• Two metals X and Y have work functions 2eV and 5eV respectively. Which metal will emit electrons, when radiated with light of wavelength 400 nm and why?
• When ultraviolet light of wavelength 300nm is incident on a metal plate, a negative potential of 0.54V is required to stop the emission of photoelectrons. Calculate the energy of the incident photon and the work function for the metal in eV?
• Show that the de Broglie wavelength for a photon is equal to the wavelength of electromagnetic radiation?

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• Which have greater total energy, if a photon and an electron have same de Broglie wavelength?
• Are matter waves electromagnetic? Explain?
• What are de Broglie waves? Describe the Davisson & Germer experiment to show the wave nature of light?
• Bright red light is not used for emission of electrons from a clean zinc surface. But even weak ultraviolet radiation can do so?
• Explain the laws of photoelectric effect on the basis of Einstein’s photoelectric effect?
• Write a note on photocell. Also, give its uses?
• Show on a graph the variation of the de Broglie wavelength () associated with an electron with the square root of accelerating potential (V).

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