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23P1Q30

30 C

This alternating voltage provides the same average power dissipation as a constant DC V₀ voltage.

23P1Q28

28 A

$\displaystyle \begin{aligned} {{E}_{photon}}&={{E}_{H}}-{{E}_{L}} \\ \frac{(6.63\times {{10}^{-34}})(3.00\times {{10}^{8}})}{\lambda }&=(122.4-30.6)(1.60\times {{10}^{-19}}) \\ \lambda &=1.35\times {{10}^{-8}}\text{ m} \end{aligned}$

23P1Q29

29 A

$\displaystyle \begin{aligned} \lambda &=\frac{h}{p} \\ \lambda p&=h \\\end{aligned}$

The product of de Brogile wavelength and momentum is the Planck constant.

23P1Q27

27 D

Option B is wrong because at least one of the diodes will be off, resulting in no current in both the positive half and negative half cycles.

23P1Q26

26 C

$\displaystyle \phi =BA$

The units for magnetic flux $\displaystyle \phi =BA$ is weber or tesla metre².

The units for magnetic flux density $\displaystyle B=\frac{\phi }{A}$ is tesla or weber metre^-2.

23P1Q25

25 D

The leftward E field causes the electron beam to be deflected rightward.

The rightward B field causes the electron beam to be deflected upward. (FLHR)

23P1Q24

24 A

A bar magnet oriented and positioned as drawn above would have created the rightward magnetic field.

23P1Q23

23 C

The resistance of the LDR decreases with intensity.

So the total resistance R should decrease with intensity, with the fixed resistance as the asymptote.

23P1Q22

22 D

The positive terminal of cell E must be facing the positive terminal of the cell in the potentiometer circuit. This rules out options A and C.

Either X or Y must be connected to the movable point P. This rules out options B and C.

Option D works.

23P1Q21

21 B

Option A: Would have been correct for “P.d. across the internal resistance of a cell”.

Option B: Correct.

Option C: Would have been correct if “total energy dissipated in it over a period of time” is replaced by “Rate of energy dissipation in the resistor (power)”.

Option D: The statement is a bit vague and unconventional but it is not totally wrong actually. Energy is converted from electrical to non-electrical in the cell due to the internal resistance of the cell. Perhaps would be more correct if “to move a unit charge” is replaced by “per unit charge moving”.