BPHET-141 · December 2023 · English
IGNOU BPHET-141 December 2023 Previous Year Question Paper
ELEMENTS OF MODERN PHYSICS
Structured previous year question paper for BPHET-141, December 2023 session.
Max marks: 50 · Questions: 9
Verified: 24 Aug 2026
BACHELOR OF SCIENCE (GENERAL)
(BSCG)
Term-End Examination
December, 2023
BPHET–141 : ELEMENTS OF MODERN PHYSICS
Time : 2 Hours Maximum Marks : 50
Note :
(i) Attempt all questions. The marks for
each question are indicated against it.
(ii) Symbols have their usual meanings.
(iii) You may use a calculator.
(iv) The values of physical constants are
given at the end.
Q1.Answer any five parts : 2×5=10
(a) What is the difference between the Galilean principle of relativity and the principle of relativity stated by Einstein ? [ 2 ] BPHET–141
(b) A rod of proper length 2.0 m measures
Q2.0 m in an inertial frame that is mo ving with respect to the rod. What is the speed of the moving frame ?
(c) Calculate the energy of a photon which has a wavelength of 500 nm.
(d) What is the minimum energy that a particle of mass m confined to a one- dimensional region of size a may have ?
(e) What is the principle on which a scanning tunneling microscope (STM) works ? What is it used for ?
(f) Show that ikxxe is an eigen function of the momentum operator with an eigen value
(g) Explain, what is an alpha decay process.
(h) What are the characteristics of a nuclear force ? [ 3 ]
Q3.Answer any two parts : 5×2=10
(a) Two events are simultaneous and separated by the distance x in an inertial frame S. Show that in an inertial frame S the events will be separat ed in both space and time.
(b) Derive the relativistic energy -momentum relationship for a free particle.
(c) A charged particle is mo ving perpendicular to a uniform magnetic field at relativistic speed in a circular orbit. Obtain the radius of the orbit.
Q4.Answer any two parts :
(a) State the key observations of the experiment on photoelectric effect. How does the quantum theory of photoelectric effect explain these observations ? 3+2 [ 4 ] BPHET–141
(b) Write down the one -dimensional time dependent Schrödinger equation. From this derive the time independent Schrödinger equation for the stationary state wave function. 1+4
(c)
(i) Calculate the de Broglie wavelength for an electron accelerated from rest through a potential difference of 200 V. 3
(ii) Calculate 2ˆˆ, xxp .
Q5.Answer any one part :
(a) A particle is confined within a length segment lying between 0x and Lx and the potential function is : 1+1+4+4
Q6.for 0 L V , for 0 and L Write down the time independent Schrödinger equation for the particle. State the boundary conditions. Obtain the normalized eigen functions. For the ground state show that ˆ 0xp= . [ 5 ] BPHET–141
(b) The potential energy function for a one - dimensional potential barrier of width L is : 3+2+5 0 , for 0 V V , for 0 L 0 , for L Write down the time independent Schrödinger equation for a particle in all three regions of this potential. State the boundary conditions on the wave function. Obtain the general solution of the Schrödinger equation in all three regions for 0EV< .
Q7.Answer any two parts : 5×2=10
(a) What is secular equilibrium ? Uranium minerals in which secular equilibrium has been obtained contain one at om of radium for every
Q8.8 10 atoms of Uranium. If the half life of radium is 1620 years, calculate the half life of uranium. 1+4 [ 6 ] BPHET–141
(b) What is the binding energy of a nucleus ? Calculate the binding energy of the nitrogen 7 N nucleus, in MeV, given that : 1+4 H1.00867 , 1.00783nm u m u and 7 N 14.00307mu . Take
Q9.5u MeV.
(c) Draw a labelled schematic diagram of a nuclear reactor. Write the function of the blanket and the reflector. 3+2 Physical constants :