Why do metals have a large number of free electrons?

Define work function of a metal. Give its unit.

What is photoelectric effect?

How does photocurrent vary with the intensity of the incident light?

Give the definition of intensity of light according to quantum concept and its unit.

How will you define threshold frequency?

State de Broglie hypothesis.

Why we do not see the wave properties of a baseball?

A proton and an electron have same kinetic energy. Which one has greater de Broglie wavelength. Justify.

Write the relationship of de Broglie wavelength λ associated with a particle of mass m in terms of its kinetic energy K.

An electron and an alpha particle have same kinetic energy. How are the de Broglie wavelengths associated with them related?

How many photons per second emanate from a 50 mW laser of 640 nm?

Calculate the maximum kinetic energy and maximum velocity of the photoelectrons emitted when the stopping potential is 81 V for the photoelectric emission experiment.

Calculate the energies of the photons associated with the following radiation:
(i) violet light of 413 nm
(ii) X-rays of 0.1 nm
(iii) radio waves of 10 m.

A 3310 Å photon liberates an electron from a material with energy 3 x10^-19 J while another 5000 Å photon ejects an electron with energy 0.972 x 10^-19 J from the same material. Determine the value of Planck’s constant and the threshold wavelength of the material.

At the given point of time, the earth receives energy from sun at 4 cal cm^–2min^–1. Determine the number of photons received on the surface of the Earth per cm² per minute. (Given: Mean wavelength of sun light = 5500 Å )

For the photoelectric emission from cesium, show that wave theory predicts that
i) maximum kinetic energy of the photoelectrons (K_max) depends on the intensity I of the incident light.
ii) K_max does not depend on the frequency of the incident light and
iii) the time interval between the incidence of light and the ejection of photoelectrons is very long.
For the sake of simplicity, the following standard assumptions can be made when light is incident on the given material.
a) Light is absorbed in the top atomic layer of the metal
b) For a given element, each atom absorbs an equal amount of energy and this energy is proportional to its cross-sectional area A.
c) Each atom gives this energy to one of the electrons.
(Given: The work function for cesium is 2.14 eV and the power absorbed per unit area is 1.60 x 10^-6 Wm^-2 which produces a measurable photocurrent in cesium.)

A radiation of wavelength 300 nm is incident on a silver surface. Will photoelectrons be observed? [work function of silver = 4.7 eV]

When light of wavelength 2200 Å falls on Cu, photo electrons are emitted from it. Find
(i) the threshold wavelength and
(ii) the stopping potential.
Given: the work function for Cu is ϕ₀ = 4.65 eV.

Calculate the cut-off wavelength and cutoff frequency of x-rays from an x-ray tube of accelerating potential 20,000 V.