Chapter 17 – Dual Nature of Radiation

An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let λn,λg be the de Broglie wavelength of the electron in the nth state and the ground state respectively. Let ⋀n be the wavelength of the emitted photon in the transition from the nth state to the ground [...]

When a certain photosensitive surface is illuminated with monochromatic light of frequency v, the stopping potential for the photo current is −V0/2. When the surface is illuminated by monochromatic light of frequency v/2, the stopping potential is −V0. The threshold frequency for photoelectric emission is : the stopping potential for the photo current is −V0/2. [...]

In a Frank-Hertz experiment, an electron of energy 5.6 eV passes through mercury vapour and emerges with an energy 0.7 eV. The minimum wavelength of photons emitted by mercury atoms is close to an electron of energy 5.6 eV passes through mercury vapour and emerges with an energy 0.7 eV. The minimum wavelength of photons [...]

A particle A of mass ‘m’ and charge ‘q’ is accelerated by a potential difference of 50 V. Another particle B of mass ‘4 m’ and charge ‘q’ is accelerated by a potential difference of 2500 V. The ratio of de-Broglie wavelengths λA/λB is close to : A 2 mW laser operates at a wavelength [...]

In a photoelectric experiment, the wavelength of the light incident on a metal is changed from 300 nm to 400 nm. The decrease in the stopping potential is close to : (hc/e=1240nm−V) In a photoelectric experiment the wavelength of the light incident on a metal is changed from 300 nm to 400 nm. The decrease [...]

If the de-Broglie wavelength of an electron is equal to 10^–3 times the wavelength of a photon of frequency 6 × 10^14 Hz then the speed of electron is equal to : Speed of light = 3 × 10^8 m/s Planck’s constant = 6.63 × 10^–34 J.s Mass of electron = 9.1 × 10^–31 kg [...]

A metal plate of area 1×10^−4m^2 is illuminated by a radiation of intensity 16 mW/m^2. The work function of the metal is 5eV. The energy of the incident photons is 10 eV and only 10% of it produces photo electrons. The number of emitted photo electrons per second and their maximum energy, respectively, will be [...]

In an electron microscope, the resolution that can be achieved is of the order of the wavelength of electrons used. To resolve a width of 7.5×10^−12m, the minimum electron energy required is close to : In an electron microscope the minimum electron energy required is close to the resolution that can be achieved is of [...]

The stopping potential V0 (in volt) as a function of frequency (v) for a sodium emitter, is shown in the figure. The work function of sodium, from the data plotted in the figure, will be : (Given : Planck’s constant (h) = 6.63 × 10^−34 Js, electron charge e = 1.6 × 10^−19 C) electron [...]

A 2 mW laser operates at a wavelength of 500 nm. The number of photons that will be emitted per second is : [Given Planck’s constant h=6.6×10^−34Js, speed of light c=3.0×10^8 m/s] A 2 mW laser operates at a wavelength of 500 nm. The number of photons that will be emitted per second is : [...]