Problem 20
The HD \(^{+}\) ion contains (1) 1 proton, 1 neutron, 1 electron (2) 2 protons, 1 neutron, 2 electrons (3) 2 protons, 1 neutron, 0 electron (4) 2 protons, 1 neutron, 1 electron
Problem 21
Which is not characteristic of Planck's quantum theory of radiation? (1) Radiation is associated with energy. (2) Energy is neither absorbed nor emitted in whole number or multiples of quanta. (3) The magnitude of energy associated with quanta is proportional to the frequency. (4) Radiation energy is neither emitted nor absorbed continuously but in small packets called quanta.
Problem 22
Find out the false statement among the following. (1) The ejection of electrons when surface of a metal is irradiated by light is known as Compton effect. (2) Light, a well-known form of energy, is treated as a form of matter by saying that it consists of photons or bundles of energy. (3) Einstein's theory of photoclectric effect is based on Planck's quantum theory. (4) In photoclectric effect, the photocurrent does not depend on the frequency of photon but depends on the intensity of incident light.
Problem 23
Among the following the correct statement(s) is/are (1) Increase in the frequency of the incident radiation increases the kinetic energy of photoelectrons. (2) Threshold wavelength depends upon work function. (3) The study of photoclectric effect is useful in understanding quantisation of energy. (4) To cross the threshold energy intensity of the light must be increased. (1) I, II and III (2) II, III and IV (3) I, III and IV (4) I, II, III and IV
Problem 24
The incorrect statement among the following is (1) Dimensions of Planek's constant are force \(\times\) time. (2) A photon is a quantum of matter. (3) Photoelectric effect shows particle-like behaviour of light. (4) The best metal to be used for photoemission is caesium.
Problem 26
Which of the following statement is correct? (1) The kinetic energy of photoclectrons increases lincarly with wavelength of the light. (2) Photoclectric effect can be explained based on corpuscular nature of light. (3) Einstein was awarded Nobel Prize in physies in 1921 for his theory of relativity. (4) The ratio of energy to frequency of electromagnetic radiation is called Rydberg's constant.
Problem 27
Photoelectric effect is the phenomenon in which (1) Photons come out of the metal when it is hit by a beam of electrons. (2) Photons come out of the nucleus of an atom under the action of an electric field. (3) Electrons come out of the metal with a constant velocity which depends on the frequency and intensity of incident light wave. (4) Electrons come out of a metal with different velocities not greater than a certain value which depends only on the frequency of the incident light wave and not on its intensity.
Problem 28
A surface ejects electrons when hit by violet light but not when hit by yellow light. Will electrons be ejected if the surface is hit by red light? (1) Yes (2) No (3) Yes, if the red beam is quite intense (4) Yes, if the red beam continues to fall upon the surface for some time
Problem 31
\(\Lambda\) light beam irradiates simultancously the surfaces of two metals \(\Lambda\) and \(B . \Lambda t\) wave length \(\lambda_{1}\) clectrons are ejected only from metal \(\Lambda . \Lambda \mathrm{t}\) wavelength \(\lambda_{2}\) both metals \(\Lambda\) and \(\mathrm{B}\) cject equal number of electrons. Then, which one of the following is false? (1) \(\lambda_{1}=\lambda_{2}\) (2) Electrons need more energy to escape from \(B\) (3) With \(\lambda_{2}\) the kinetic energy of electrons emitted from \(\Lambda\) is less than that of electrons from \(\mathrm{B}\) (4) Electrons emitted from \(\Lambda\) have the greater kinetic energy when produced by \(\lambda_{2}\) light
Problem 32
The ratio of the energy of photon \(2000 A\) wavelength radiation to that of \(4000 A\) radiation is (1) \(1 / 4\) (2) \(1 / 2\) (3) 2 (4) 4
