111年 - [非官方正解]111 國立臺灣大學_碩士班招生考試：普通物理學#125318

1. What is the average net torque on the wheel during this time interval?
(A) (B)(C) (D)(E)

2. What is the average power input to the wheel during this time interval?
(A) (B) (C) (D)(E)

3. What is the ratio of
(A) 2½ (B) (C) (D) (E)

4. What is the entropy change along the A to D process? (A) nCvln2 (B) nCvln3/2 (C) nCvln2(D) (E) 0

5. What is the total heat transferred during the full cycle?
(A) 5nRT₁ (B) 2nRT₁ln3 (C) 2nRT₂ln2 (D) 5nRT₁ln2 (E) 6nRT₂ln3

6. What is the efficiency of this engine? (A) (B) (C)(D) (E)

7. What is the acceleration of the cylinder as it rolls down the incline?
(A)gsinθ (B)gcosθ (C)gcosθ (D)gtanθ (E)gtanθ

8. What is the minimum coefficient of friction necessary for the cylinder to roll without slipping down the ramp? (A)(B) (C) (D) (E)

9. What is the oscillating amplitude of ratioof m₂ (Δx₂) over m₁ (Δx₁)?
(A) (B)(C) (D) (E)

10. What is the natural angular frequency of the system?
(A)(B)(C)(D)(E)

11. Two infinite planes of constant surface charge densities σ₁and σ₂  are located at z = -1 and z = 1, respectively, both parallel to the x-y plane. What is the electric field in the range 1 ＞ z ＞ -1?(A)(B)(C)(D)(E) E = 0.

12. Which statement below is correct? (In the following, log denotes natural log.)
(A)(B)(C)(D)(E)

13. What is the electric potential for R₁ ＞ r ＞ 0?
(A) (B)(C)(D)(E)

14. What is the potential difference V_C on the capacitor and the current I_L on the inductor at t = 0⁺, instantaneously after the circuit is closed?(A)V_C = 0, I_L = 0.(B) V_C = 0, I_L = V₀/R₂. (C)V_C = V₀/R₁, I_L = 0. (D) V_C = V₀, I_L = 0. (E) V_C = V₀, I_L = V₀/R₂.

15. What happens in the limit t → ∞?(A)V_C = 0, I_L = 0. (B) V_C = 0, I_L = V₀/R₂. (C) V_C = V₀/R₁, I_L = 0.(D) V_C = V₀, I_L = 0.(E)V_C = V₀, I_L = V₀/R₂.

16. Which statement below is correct?(A) Two capacitors C₁, C₂ in parallel is equivalent to the capacitance of (C1^-1+ C₂^-1), (B)The potential energy of a capacitor
C at potential difference V equals CV², (C) Maxwell’s equations imply charge conservation,(D) Maxwell’s equations imply the Lorentz force law. (E) The (volume) energy density for a magnetic field B in vacuum is

17. A background of magnetic field B(x, y) =(a + by)x is prepared on the x-y plane for given constants a and b. A rectangular loop (see figure) moves at a constant velocity v. The bottom of the loop coincides with the x axis, and its left side is at x = 0 when t = 0. What is the induced emf on the loop at time t? (z direction points out of plane.)(A) (a + bh)Lv clockwise. (B) (a + bh)Lv counter-clockwise. (C) (ah + bh²/2)Lv clockwise. (D) (ah + bh²/2)Lv counter-clockwise. (E) 0.

18. Which statement below is correct? (A) A point charge at constant velocity radiates due to Lorentz contraction. (B) A point charge in free fall in a gravitational field feels no back-reaction force. (C) A point charge in free fall does not radiate. (D) A radiation in an inertial frame may appear like vacuum in another inertial frame. (E) The energy radiated from an accelerating point charge per unit time is the same in every inertial frame.

19. An electromagnetic wave in vacuum has the electric field E = E₀cos(ωt - kx)x, where ω = ck. What is the magnetic field?
(A) B = sin(ωt - kx)y. (B) B =CE₀sin(ωt + kz)z. (C) B =cos(ωt - kx)z. (D) B = cE₀cos(ωt + kz)z.(E) B =cE₀sin(ωt - kx)y.

20. Which statement below is correct? (A) In the double-slit experiment, it would be easier to see the double-slit interference pattern if the width of the slits is larger than the distance between the slits. (B) Electromagnetic plan waves have 3 independent polarizations. (C) The sky is blue because it reflects the image of the sea. (D) For a small spherical mirror of radius R, its focus is R/2. (E) The rainbow appears in the direction of the sun.