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Ashok0210

Asked: April 27, 2021In: Class 12 Physics

(a) Obtain the de Broglie wavelength of a neutron of kinetic energy 150 eV. As you have seen in Exercise 11.31, an electron beam of this energy is suitable for crystal diffraction experiments. Would a neutron beam of the same energy be equally suitable? Explain. (mn = 1.675 × 10⁻²⁷ kg) (b) Obtain the de Broglie wavelength associated with thermal neutrons at room temperature (27 ºC). Hence explain why a fast neutron beam needs to be thermalised with the environment before it can be used for neutron diffraction experiments.

$(a) Obtain the de Broglie wavelength of a neutron of kinetic energy 150 eV. As you have seen in Exercise 11.31, an electron beam of this energy is suitable for crystal diffraction experiments. Would a neutron beam of the same energy be equally suitable? Explain. (mn = 1.675 × 10⁻²⁷ kg) (b) Obtain the de Broglie wavelength associated with thermal neutrons at room temperature (27 ºC). Hence explain why a fast neutron beam needs to be thermalised with the environment before it can be used for neutron diffraction experiments.$

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.32 NCERT Solutions for Class 12 Physics Chapter 11 Question-32 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

Crystal diffraction experiments can be performed using X-rays, or electrons accelerated through appropriate voltage. Which probe has greater energy? (For quantitative comparison, take the wavelength of the probe equal to 1 Å, which is of the order of inter-atomic spacing in the lattice) (me=9.11 × 10⁻³¹ kg).

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.31 NCERT Solutions for Class 12 Physics Chapter 11 Question-31 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

Light of intensity 10⁻⁵ W m⁻² falls on a sodium photo-cell of surface area 2 cm² . Assuming that the top 5 layers of sodium absorb the incident energy, estimate time required for photoelectric emission in the wave-picture of radiation. The work function for the metal is given to be about 2 eV. What is the implication of your answer?

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.30 NCERT Solutions for Class 12 Physics Chapter 11 Question-30 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

The work function for the following metals is given: Na: 2.75 eV; K: 2.30 eV; Mo: 4.17 eV; Ni: 5.15 eV. Which of these metals will not give photoelectric emission for a radiation of wavelength 3300 Å from a He-Cd laser placed 1 m away from the photocell? What happens if the laser is brought nearer and placed 50 cm away?

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.29 NCERT Solutions for Class 12 Physics Chapter 11 Question-29 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

A mercury lamp is a convenient source for studying frequency dependence of photoelectric emission, since it gives a number of spectral lines ranging from the UV to the red end of the visible spectrum. In our experiment with rubidium photo-cell, the following lines from a mercury source were used: λ ₁ = 3650 Å, λ ₂= 4047 Å, λ ₃ = 4358 Å, λ₄ = 5461 Å, λ₅ = 6907 Å, The stopping voltages, respectively, were measured to be: V0₁ = 1.28 V, V0₂= 0.95 V, V0₃= 0.74 V, V0₄ = 0.16 V, V0₅ = 0 V Determine the value of Planck’s constant h, the threshold frequency and work function for the material. [Note: You will notice that to get h from the data, you will need to know e (which you can take to be 1.6 × 10⁻¹⁹C). Experiments of this kind on Na, Li, K, etc. were performed by Millikan, who, using his own value of e (from the oil-drop experiment) confirmed Einstein’s photoelectric equation and at the same time gave an independent estimate of the value of h.]

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.28 NCERT Solutions for Class 12 Physics Chapter 11 Question-28 Additional Exercise

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