物理波的現象 DSE、CE 選擇題（第 3 頁）

21.

Pulse PQ travelling towards a V-shaped barrier in a ripple tank

A straight pulse $PQ$ travels towards a $V$ -shaped barrier in a ripple tank as shown above. Which of the following diagrams best shows the reflected pulse(s) ?

Four diagrams A to D of reflected pulses at a V-shaped barrier

22.

Straight water waves in a ripple tank on the left, a question mark in the middle region, and curved waves on the right

A series of straight water waves travels towards the right in a ripple tank as shown above. In order to obtain the waves in the right hand side, what kinds of phenomenon have the straight waves undergone ?

23.

A plane water wave travels from a deep region to a shallow region of water. If the wavelength, frequency and speed of the wave in the deep region are $\lambda_1$ , $f_1$ and $v_1$ respectively, while the corresponding values in the shallow region are $\lambda_2$ , $f_2$ and $v_2$ respectively. Which of the following relations is/are correct ?

(1)

\lambda_1>\lambda_2

(2)

v_1>v_2

(3)

f_1>f_2

24.

Plane water waves in a shallow region meeting the boundary with a deep region at an angle

The diagram above shows a series of plane water waves travelling from a shallow region to a deep region of water. Which of the following diagrams best shows the wave pattern in the deep region ?

$Four refraction diagrams A to D$

25.

A series of plane water waves travel towards an obstacle in a ripple tank. When the waves pass the obstacle, they bend around the corners of the obstacle. Which of the following statements is/are correct ?

(1)The phenomenon is called diffraction.

(2)The speed of the waves remains unchanged as they bend round the corners.

(3)The degree of bending of the waves depends on the size of the obstacle relative to the wavelength of the waves.

26.

Stationary wave on a string of length 1 m with particles P, Q and R marked

A vibrator generates a stationary wave on a string. The above diagram shows the string at the instant of maximum displacement. Which of the following statements is incorrect ?

27.

Questions 23 and 24 : A vibrator generates a stationary wave on a string. The diagram below shows the string at a certain instant.

Stationary wave on a string between a vibrator and a fixed end, with particles X and Y marked

Which of the following statements is incorrect ?

28.

Questions 23 and 24 : A vibrator generates a stationary wave on a string. The diagram below shows the string at a certain instant.

The vibrating string also sets the neighbouring air into vibration. Which of the following statements about the waves on the string and those in air must be correct ?

29.

Vibrator producing plane waves in a ripple tank towards a slit in a barrier

A vibrator generates continuous plane waves in a ripple tank. The waves undergo diffraction when they pass through a slit. Which of the following can increase the degree of diffraction of the waves ?

(1)Increasing the width of the slit

(2)Placing the vibrator closer to the slit

(3)Increasing the wavelength of the water waves

30.

Figure (a): vibrator dipping into a ripple tank of water. Figure (b): plane wave pattern from the vibrator

A vibrator generates continuous plane waves in a ripple tank (see Figure (a)). Figure (b) shows the wave pattern observed.

Figure (c): the ripple tank tilted so the water depth varies

Now the ripple tank is tilted as shown in Figure (c). Which of the following diagrams best shows the wave pattern observed ?

Four wave patterns A to D with different wavefront spacings