Practice Test 12 - AP Physics 2

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. A ray of light passes from air into a clear plastic slab. The plastic has higher refractive index than air ($n_{plastic} > n_{air}$). The incident angle is nonzero, and the ray enters the plastic. Which statement best describes the direction of the refracted ray?
2. A bar magnet is held fixed near a conducting loop. The loop is then moved away so the magnetic field strength through the loop decreases. Which statement correctly describes the induced current (viewed from the magnet side)?
3. An EM wave travels in the $+z$ direction through vacuum. A probe measures the electric field oscillating along $+x$ and the magnetic field oscillating along $+y$. Which statement best describes electromagnetic waves?
4. A laser illuminates two narrow slits, producing alternating bright and dark fringes on a distant screen. At point $P$ the two paths differ by $1.5\lambda$. Which observation occurs at $P$? (Path difference determines whether waves arrive in phase.)
5. A device has a constant current $I$ through it for $10\text{ s}$. During that time its voltage drops linearly from $12\text{ V}$ to $6\text{ V}$. Compared to the beginning, the instantaneous power at the end is
6. At junction $J$, current $I_1$ enters and splits into currents $I_2=0.40\ \text{A}$, $I_3=0.60\ \text{A}$, and $I_4$ leaving as labeled. Which statement correctly applies Kirchhoff's junction rule?
7. A $0.40\,\text{kg}$ lead sphere at $70^\circ\text{C}$ is dropped into a large insulated bath of oil initially at $20^\circ\text{C}$. The sphere remains submerged until equilibrium is reached. Which statement best describes the direction of thermal energy flow?
8. A nuclide can decay by either $\beta^{+}$ emission or electron capture. Both leave the daughter with:
9. A thin converging lens has focal length $f=+10\ \text{cm}$. An object is placed 6 cm to the left of the lens. A ray diagram is drawn using a center ray and a parallel ray. Which statement best describes the image?
10. A $-0.80\,\mu\text{C}$ charge is moved from point E at $V_E=-50\,\text{V}$ to point F at $V_F=-20\,\text{V}$ in a static electric field. As the charge moves from E to F, the electric potential energy _____.
11. A $+2.0\,\mu\text{C}$ charge moves from a point at $V=+30\,\text{V}$ to a point at $V=+10\,\text{V}$ in an external electric field. As the charge moves, the electric potential energy of the charge-field system changes. Which statement correctly describes the change in electric potential energy?
12. $^{210}_{84}\text{Po}$ decays into $^{206}_{82}\text{Pb}$. Which type of radioactive decay produces this change?
13. A sinusoidal wave on a string has speed $12\ \text{m/s}$ and wavelength $3.0\ \text{m}$. The amplitude is doubled while the string and tension remain unchanged. Which quantity changes for the wave?
14. A pipe is open at one end and closed at the other, and it supports a standing sound wave at $f=255\,\text{Hz}$. The diagram labels a displacement node at the closed end and a displacement antinode at the open end. The pattern shown has one additional interior node. Which harmonic (mode number) is shown for this open-closed pipe?
15. A closed single-loop circuit contains an ideal $8.0\,\text{V}$ battery and two identical resistors in series. Compared to a circuit with only one of those resistors, which statement best describes the current?
16. An inventor claims a heat engine between $T_h=400\,\text{K}$ and $T_c=200\,\text{K}$ has efficiency $\eta=0.80$; the claim implies a non-spontaneous violation if true. Which conclusion is consistent with the second law?
17. The spontaneous transfer of energy between two objects in thermal contact always occurs in a specific direction. Which of the following principles governs this directionality?
18. A $6\ \text{V}$ ideal battery connects to $R_1=1\ \Omega$ in series, then reaches junction $J$ where it splits into two branches that rejoin at $K$. Branch 1 has $R_2=2\ \Omega$; Branch 2 has $R_3=6\ \Omega$. Which statement correctly compares the currents through $R_2$ and $R_1$?
19. A nucleus changes from $^{99}_{43}\text{Tc}$ to $^{99}_{44}\text{Ru}$. Which type of decay occurs?
20. A capacitor has charge $Q=30\,\mu\text{C}$ and capacitance $C=6.0\,\mu\text{F}$, and it is isolated. Which conclusion is correct about the voltage across it?

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