UNIT -1 BITS Physics Multiple Choice Questions PDF

# Multiple Choice Questions 1. Davisson and Germer experiment is related to - Interference - electron diffraction - polarization - verification of Bohr's theory 2. The wavelength λ associated with a particle of mass m moving with velocity u is given by - h/mv - hv/m - m...

# Multiple Choice Questions 1. Davisson and Germer experiment is related to - Interference - electron diffraction - polarization - verification of Bohr's theory 2. The wavelength λ associated with a particle of mass m moving with velocity u is given by - h/mv - hv/m - mv/h - m/hv 3. The de Broglie wave associated with a moving particle is - An infinite monochromatic wave - a finite monochromatic wave train - a wave packet having a group velocity equal to that of the moving particle - None 4. The de Broglie wavelength of a particle is proportional to - Its mass - its velocity - inversely to its momentum - None 5. If an electron is accelerated from rest to a velocity u by a potential of V volts, the its wavelength is - λ=(h/√2emV) - λ = √h/2emV - λ = (h/√emv) - λ = √h/2emV 6. Which of the following particles moving with the same velocity has longest waves associated with it? - Proton - electron - neutron - a-particle 7. When an electron is accelerated by a potential V, then its de Broglie wavelength is - (12.27/√)A - (1.227/V)Α - (1227/√)A - (122.7/√√)Å 8. The probability of finding the particle within an elemental volume, dV is given by - ∫ψψ* dV - ψ dV - ∫|ψ|² dV - ∫|ψ|² dv # 42 Applied Physics for Engineers 9. A wave function ψ is normalized, if - ∫ψψ*dV = 0 - ∫ψψ* dV = V - ∫|ψ|² dv = 1 - ∫ψψ* dV = 1 10. A proton and an α-particle are accelerated through the same potential difference, V. The wavelengths associated with the two have the ratio - √2:1 - 2√2:1 - 2:1 - 4:1 11. The expression of the momentum of a photon is: - qp = hλ - qp = h/λ - qp = c/λ - None 12. The energy of a photon, expressed in eV, the visible light of wavelength λ = 634 nm is equal to: - q E = 1.95 eV - q E = 19.5 eV - q E = 0.195 eV - None 13. The wavelength, expressed in nm, of a photon of energy equal to 1 keV is equal to: - q λ = 0.124 nm - q λ = 1.24 nm - q λ = 12.407 nm - None 14. The wavelength associated with an electron of energy E = 100 eV is equal to: - q 1.23nm - q 12.3 nm - q 123 nm - None 15. The wavelength associated with a 2 g ball with a velocity of 100 m/s is equal to: - q 3.31 × 10-33 m - q 3.31 × 10-30 m - q 2.38 × 10-24 m - None 16. The wave function for a particle must be normalizable because the particle's - Charge must be conserved - momentum must be conserved - must be somewhere - None 17. De-Broglie wavelength associated with an accelerated charged particle - λ = 2h/√2emV - λ = h/√2emV - λ = h/√emV - None 18. Relation between Phase Velocity and Group Velocity - υg = υp + λ dυp/dλ - υg = υp - λ dυp/dλ - υg = υp - λ dυp/αλ - None 19. Energy - Momentum Uncertainty relation is: - Δy. Δpy ≥ ħ/2 - Δz. Δpz ≥ ħ/2 - ΔΕ. Δt ≥ ħ/2 - None 20. In Probability P = |ψ(x, y, z)|²dV conditions to be satisfied by ψ-function - Must be finite - single-valued - continuous - All # Answer Keys 1. (c) 2. (a) 3. (c) 4. (c) 5. (a) 6. (b) 7. (b) 8. (a) 9. (d) 10. (c) 11. (b) 12. (a) 13. (b) 14. (b) 15. (a) 16. (c) 17. (b) 18. (c) 19. (c) 20. (d) # Fill Up the blanks 1. Heisenberg's theory came to be known as **matrix** mechanics while that of Schrödinger as **wave** mechanics. 2. The waves associated with particles are known as **matter waves**. 3. The wavelength λ of matter waves associated with a particle moving with velocity u is inversely proportional to the magnitude of the **momentum**. 4. The expression λ = h/p = h/mv is known as **De-Broglie wavelength**. 5. De-Broglie wavelength expressed in terms of K.E. 6. De Broglie theory shows that the quantization of angular momentum is a direct consequence of **wave nature of electron**. 7. De Broglie waves cannot be **harmonic** waves. 8. The velocity with which the wave packet propagates is called the **group velocity**. 9. The time-dependent Schrödinger equation for three dimensional motion - ħ²/2m * ∇²ψ + Vψ = Εψ 10. The expression ħ²/2m * ∇²ψ + Vψ = Εψ is **a time-independent Schrödinger equation**. 11. A particle is said to be a **free particle** when it is moving in space without being subjected to any external force in any region of space, and its V is constant everywhere. 12. In classical theory, a particle in a box can have energy of zero value. The **quantum theory** shows that a particle in a box cannot have zero energy. 13. The minimum energy possessed by the particle is E₁ = **h²/8mL²**. 14. For different combinations of quantum numbers, we may obtain the same energy value but the wave functions are different. Such quantum states having the same energy are called **degenerate**. 15. Uncertainty principle is not significant in case of **macro-bodies**. 16. To make probability wave function ψ a real quantity, ψ is to be multiplied by its **complex conjugate ψ**. 17. |ψ|² gives the **probability density** in a particular region. 18. In the normalization condition, ∫ψ(x, y, z,t)² dxdydz is called the **normalization constant**. 19. The probability of finding the particle between x and x + dx is given by **P dx = ψ*(x, t)ψ(x, t)dx**. 20. The individual waves forming the wave packet propagate at a velocity known as the **phase velocity υp**.