物理波的現象 DSE、CE 選擇題（第 2 頁）

11.

Waveform of a transverse stationary wave with P at its lowest position and Q on the equilibrium line

The figure shows the waveform of a transverse stationary wave at a certain instant. If particle $P$ is at its lowest position at this instant, what will be the instantaneous motion of particles $P$ and $Q$ after a quarter of a period ?

	$P$	$Q$
	moving upwards	at rest
	moving upwards	moving upwards
	at rest	at rest
	at rest	moving upwards

12.

$Ripple tank with a vibrator, plane waves, and an obstacle with a gap producing diffracted waves$

A student uses the above set-up to study the diffraction of water waves. Which of the following changes can make the diffraction effect more significant ?

(1)reducing the width of the gap between the obstacles

(2)increasing the frequency of the vibrator

(3)adding more water to the ripple tank

13.

Two dippers S1 and S2 with dashed lines to a point P in a ripple tank

Two dippers $S_1$ and $S_2$ are connected to the same vibrator and produce identical waves in a ripple tank. $P$ is a point such that $S_1P-S_2P=\lambda$ , where $\lambda$ is the wavelength of the water waves generated. Which of the following statements is/are correct ?

(1)Constructive interference occurs at

P

.

(2)A crest is always formed at

P

.

(3)If the wavelength of the waves generated by the dippers is doubled, destructive interference will occur at

P

.

14.

Plane water waves travelling to the right towards an L-shaped barrier

Plane water waves travels towards an L-shaped barrier in a ripple tank as shown above. Which of the following diagrams best shows the reflected wave pattern ?

Four diagrams A to D of reflected wave patterns at an L-shaped barrier

15.

Plane waves moving from a deep region towards a narrow gap in an obstacle with a shallow region beyond

Plane water waves travel from a deep region to a shallow region of water through a narrow gap as shown above. Which of the following properties of the waves remains unchanged ?

16.

In a ripple tank experiment, a series of water waves travels towards a barrier. Which of the following quantities would remain unchanged after the waves are reflected by the barrier ?

(1)wavelength

(2)frequency

(3)speed

17.

Ripple tank with spongy lining, plane water waves travelling towards an opening in a barrier

Which of the following phenomena would be observed when the water waves pass through the opening in the above set-up ?

18.

Boundary XY between a deep region and a shallow region with straight waves approaching obliquely from the deep region

In the above diagram, $XY$ represents a boundary between a deep region and a shallow region of water in a ripple tank. A series of straight water waves in the deep region travels towards $XY$ . Which of the following diagrams best shows the wave pattern in the shallow region ?

$Four refraction diagrams A to D$

19.

Water waves of wavelength $\lambda$ are diffracted as they pass through a gap of width $d$ as shown in the figure above. Which of the following changes would produce the most significant diffraction effect ?

$Plane water waves passing through a gap of width d in a barrier and diffracting$

	$\lambda$	$d$
	remains unchanged	halved
	remains unchanged	doubled
	halved	halved
	halved	doubled

20.

A water wave of frequency $30$ Hz travels in a deep region of water. When the wave enters a shallow region, its wavelength is reduced to one-third of its original value. Find the frequency of the water wave in the shallow region.