MCQ on Crystal Oscillations with Answers
Q1. Which of the following statements is NOT correct ?
- (A) Acoustic branch of diatomic linear chain is similar to the monoatomic case
- (B) Both group velocity and phase velocity are equal to the velocity of sound in the long wavelength limit
- (C) Under the low wavelength limit, the lattice acts as a low pass filter
- (D) Acoustic and optical modes in diatomic lattice cancel each other at the boundary of first Brillouin zone
Q2. In the Kronig-Penney model, the discontinuous in the E vs k curve occur on either side of the centre for a k-value equal to (where n = 1, 2, 3, ….)
- (A) nπ/a
- (B) nπ/2a
- (C) √(nπ/2a)
- (D) (2nπ)/a
Q3. Which of the following statements is correct for NaCl crystal structure?
- (A) It is a simple cubic lattice with one atom basis.
- (B) It is a face-centered cubic lattice with one atom basis
- (C) It is a simple cubic lattice with two atom basis
- (D) It is a face-centered cubic lattice with two atom basis.
Q4. Which of the following is the best technique for measuring the effective mass of an electron in a semiconductor?
- (A) Resistivity measurements
- (B) Cyclotron resonance
- (C) X-rays diffraction experiment
- (D) Millikan’s oil drop experiment
Q5. Which of the following statements is true about the velocity of electron in an energy band ?
- (A) It is constant throughout the band
- (B) It is maximum at the bottom of the band
- (C) It is maximum at the inflection point of the E(k) curve
- (D) It is maximum at the top of the band
Q6. In one-dimensional periodic chain of atom with lattice parameter ‘a’ has first brillouin zone at:
- (A) a
- (B) 2a
- (C) π/a
- (D) 2π/a
Q7. The origin of van der Waal’s interaction in molecular crystal is
- (A) nuclear
- (B) magnetic
- (C) Ionic
- (D) fluctuating dipolar
Q8. In the Kronig-Penney model, electrons are assumed to be moving in
- (A) one-dimensional square well potential
- (B) one-dimensional square well periodic
- (C) potential three-dimensional coulomb
- (D) potential a periodic harmonic potential
Q9. Indicate the false conclusion drawn from the Kronig-Penney model of band theory of
- (A) the energy spectrum consists of a number of allowed energy bands separated by forbidden regions
- (B) the width of allowed energy bands decreases with increasing energy
- (C) the width of a particular energy band decreases with increasing binding energy of the solid
- (D) the total number of possible wave functions in any energy band is equal to the number of unit cells.
Q10. In the expression for bonding force F(r) = (A/rm) – (B/rn) [ n > m, (A, B) = constant) if n takes the value between 7 and 10, the bonding is called as
- (A) lonic
- (B) Covalent
- (C) Metallic
- (D) Dipole
|NOTE:- If you need anything else like e-books, video lectures, syllabus, etc. regarding your Preparation / Examination then do 📌 mention it in the Comment Section below.|
Answer Key (if you find any answer wrong, feel free to Correct us)