CBSE class 12th Physics - Photo electric effect

In this article you will get the clue that from where and how the questions are being framed from the topic Photo electric effect
The experts of jagranjosh.com have full confidence that you will not miss any of the questions in the board exam as well as in competitive exams from this chapter if you will keep the following terms / question in your mind while studying

Introduction and contributions of some scientists for one marks questions

Which rays can cause Photo electric effect?

Photo electric effect supports plank’s quantum theory of light and particle nature of light.

How?

What is the meaning of intensity and energy of a photon in modern physics?

Leonard postulates for Photo electric effect

Kinetic energy of ejected electron depends either on energy or intensity of incident photon

Threshold frequency and threshold wave length

Derivation of formula to get the mass of a moving photon from plank’s hypothesis and Einstein's mass energy equation

Work function, its dependency for the different materials and for the different layers of the same material

Is there any effect of work function on current?

Relation of kinetic energy with work function

Graph between kinetic energy of electron and frequency of incident photon and then slope of the graph

Graph between stopping potential and frequency of incident photon and then slope of the graph

Relation between intensity of incident photon and photo current

Graph based calculations

Get the help from here while solving the problems based ob de Broglie hypothesis

Sample Questions:

Q.1 If the two electrons are getting incident on the same layer of the metal with different wave length and different frequency. Then derived the relations of their kinetic energies

Q2. The work function of caesium metal is 2.14 eV. When light of frequency 6 ×1014Hz 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?

Q3. 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.

Q4. What is the de Broglie wavelength of
      (a) a bullet of mass 0.040 kg travelling at the speed of 1.0 km/s,
      (b) a ball of mass 0.060 kg moving at a speed of 1.0 m/s, and
      (c) a dust particle of mass 1.0 × 10–9 kg drifting with a speed of 2.2 m/s?

Q.5. what is the de Broglie wavelength of a nitrogen molecule in air at 300 K? Assume that the molecule is moving with the root-mean square speed of molecules at this temperature. (Atomic mass of nitrogen = 14.0076 u)

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