Practice Test 6 - AP Physics 2

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

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1. X-rays scatter from a graphite target and show a shift in wavelength that depends on scattering angle. Classical wave theory cannot explain a wavelength change from scattering off free electrons. Which statement best explains what this indicates about electromagnetic radiation?
2. A plane mirror is rotated by $10^\circ$ while a laser's incident direction in air stays fixed. The reflected direction changes accordingly. Which statement correctly describes the reflection?
3. Positive charges drift steadily to the right through a conducting fluid. Which statement best describes the conventional current direction?
4. An electron ($q=-1.60\times10^{-19}\,\text{C}$) travels upward at $2.5\times10^{6}\,\text{m/s}$ through a uniform magnetic field $B=0.30\,\text{T}$ directed to the right. No electric field acts. Which statement best describes the direction of the magnetic force on the electron?
5. A drone emits a steady tone while flying at constant speed past a stationary observer in still air. At the instant the drone is moving directly away, compared to when it was approaching, the observed frequency is
6. A beam of electrons passes one at a time through a double slit and is detected on a distant screen. Individual detections appear as localized dots, but after many electrons an interference fringe pattern emerges. Classical physics cannot explain how single particles build an interference pattern. Which statement best explains this phenomenon?
7. Two pulses travel toward each other on a taut string. Pulse 1 is a $+2.0\,\text{cm}$ crest; pulse 2 is a $-2.0\,\text{cm}$ trough of the same shape and width. At the instant they completely overlap, what is the string's displacement in the overlap region?
8. A $1.0\,\text{kg}$ ice–water mixture at $0^\circ\text{C}$ is left in a $20^\circ\text{C}$ room. Heat flows from the room into the mixture and eventually all the ice melts; this process is spontaneous. Which conclusion is consistent with the second law for the room+mixture system?
9. A $2.0\,\mu\text{F}$ capacitor is connected to a $6.0\,\text{V}$ battery. If the battery is replaced by a $12\,\text{V}$ battery, what happens to $Q$?
10. A device transfers $120\text{ J}$ of electrical energy to thermal energy in $4.0\text{ s}$ while the current remains steady. Which statement about the device's average power is correct?
11. A student observes dark absorption lines after light passes through a cool gas. Which statement best describes what happens to an electron in an atom during absorption?
12. A fully charged capacitor is connected to a resistor, so it is discharging. Which statement best describes the capacitor's voltage $V_C$ at long times?
13. A periodic wave on a string has period $T=0.25\ \text{s}$. Which statement best describes its frequency?
14. A blackbody is heated, and its emission curve shifts and grows. As temperature increases, which statement correctly describes the peak intensity and peak wavelength together?​
15. A string of length $1.20\,\text{m}$ is fixed at both ends and driven at a frequency that produces the standing-wave pattern shown. Points $N_1$, $N_2$, and $N_3$ are labeled as nodes, and points $A_1$ and $A_2$ are labeled as antinodes. The string's shape oscillates in time, but the node locations remain fixed. Which statement correctly describes the motion at a node compared with an antinode?
16. A closed single-loop circuit contains an ideal $3.0\ \text{V}$ battery and one resistor. The current is $0.60\ \text{A}$. The battery is replaced with an ideal $6.0\ \text{V}$ battery while keeping the same resistor and a closed loop. Which statement best describes the new current?
17. A nucleus changes from $^{22}_{11}\text{Na}$ to $^{22}_{10}\text{Ne}$. Which type of decay occurs?
18. A closed system of gas undergoes a process. Take $Q>0$ into the system and $W>0$ done by the system. Measurements show the internal energy increases by $\Delta U=+400\,\text{J}$ while the gas does $W=+150\,\text{J}$ of work. Which statement correctly gives the heat transferred?
19. A $^{137}\mathrm{Cs}$ nucleus undergoes gamma emission after a prior decay step. Which statement best describes gamma emission?
20. A vertical wire carries current downward through a uniform magnetic field out of the page. Which statement best describes the magnetic force on the wire?

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