Class 12 Physics

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

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

Monochromatic radiation of wavelength 640.2 nm (1nm = 10⁻⁹ m) from a neon lamp irradiates photosensitive material made of caesium on tungsten. The stopping voltage is measured to be 0.54 V. The source is replaced by an iron source and its 427.2 nm line irradiates the same photo-cell. Predict the new stopping voltage.

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.27 NCERT Solutions for Class 12 Physics Chapter 11 Question-27 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

Ultraviolet light of wavelength 2271 Å from a 100 W mercury source irradiates a photo-cell made of molybdenum metal. If the stopping potential is –1.3 V, estimate the work function of the metal. How would the photo-cell respond to a high intensity (∼10⁵ W m⁻²) red light of wavelength 6328 Å produced by a He-Ne laser?

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.26 NCERT Solutions for Class 12 Physics Chapter 11 Question-26 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

Estimating the following two numbers should be interesting. The first number will tell you why radio engineers do not need to worry much about photons! The second number tells you why our eye can never ‘count photons’, even in barely detectable light. (a) The number of photons emitted per second by a Medium wave transmitter of 10 kW power, emitting radiowaves of wavelength 500 m. (b) The number of photons entering the pupil of our eye per second corresponding to the minimum intensity of white light that we humans can perceive (∼10⁻¹⁰ W m⁻²). Take the area of the pupil to be about 0.4 cm² , and the average frequency of white light to be about 6 × 10¹⁴ Hz.

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.25 NCERT Solutions for Class 12 Physics Chapter 11 Question-25 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

In an accelerator experiment on high-energy collisions of electrons with positrons, a certain event is interpreted as annihilation of an electron-positron pair of total energy 10.2 BeV into two γ-rays of equal energy. What is the wavelength associated with each γ-ray? (1BeV = 10⁹ eV)

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.24 NCERT Solutions for Class 12 Physics Chapter 11 Question-24 Additional Exercise

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

In an experiment on photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be 4.12 × 10⁻¹⁵ V s. Calculate the value of Planck’s constant

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.6 NCERT Solutions for Class 12 Physics Chapter 11 Question-6

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

The energy flux of sunlight reaching the surface of the earth is 1.388 × 10³ W/m² . How many photons (nearly) per square metre are incident on the Earth per second? Assume that the photons in the sunlight have an average wavelength of 550 nm

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.5 NCERT Solutions for Class 12 Physics Chapter 11 Question-5

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

Monochromatic light of wavelength 632.8 nm is produced by a helium-neon laser. The power emitted is 9.42 mW. (a) Find the energy and momentum of each photon in the light beam, (b) How many photons per second, on the average, arrive at a target irradiated by this beam? (Assume the beam to have uniform cross-section which is less than the target area), and (c) How fast does a hydrogen atom have to travel in order to have the same momentum as that of the photon?

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.4 NCERT Solutions for Class 12 Physics Chapter 11 Question-4

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

The photoelectric cut-off voltage in a certain experiment is 1.5 V. What is the maximum kinetic energy of photoelectrons emitted?

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.3 NCERT Solutions for Class 12 Physics Chapter 11 Question-3

Ashok0210

Asked: April 27, 2021In: Class 12 Physics

The work function of caesium metal is 2.14 eV. When light of frequency 6 ×10¹⁴ Hz is incident on the metal surface, photoemission of electrons occurs. What is the (a) maximum kinetic energy of the emitted electrons, (b) Stopping potential, and (c) maximum speed of the emitted photoelectrons?

Class 12 Physics CBSE and UP Board Dual Nature of Radiation and Matter Chapter-11 Exercise 11.2 NCERT Solutions for Class 12 Physics Chapter 11 Question-2

Category: Class 12 Physics

In an accelerator experiment on high-energy collisions of electrons with positrons, a certain event is interpreted as annihilation of an electron-positron pair of total energy 10.2 BeV into two γ-rays of equal energy. What is the wavelength associated with each γ-ray? (1BeV = 10⁹ eV)

In an experiment on photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be 4.12 × 10⁻¹⁵ V s. Calculate the value of Planck’s constant

The energy flux of sunlight reaching the surface of the earth is 1.388 × 10³ W/m² . How many photons (nearly) per square metre are incident on the Earth per second? Assume that the photons in the sunlight have an average wavelength of 550 nm

The photoelectric cut-off voltage in a certain experiment is 1.5 V. What is the maximum kinetic energy of photoelectrons emitted?

The work function of caesium metal is 2.14 eV. When light of frequency 6 ×10¹⁴ Hz is incident on the metal surface, photoemission of electrons occurs. What is the (a) maximum kinetic energy of the emitted electrons, (b) Stopping potential, and (c) maximum speed of the emitted photoelectrons?

Which is the best website providing NCERT Solutions?

NCERT Books

Where can I get NCERT books in PDF format?

NIOS

NCERT Solutions

Sign Up

Sign In

Forgot Password

Category: Class 12 Physics

Tiwari Academy Discussion Latest Questions