Which of the following wave motions may be used to demonstrate the phenomenon of polarisation?

Baca Juga

• A uniform beam of mass 1.4 kg is pivoted at P as shown. The beam has a length of 0.60 m and P is 0.20 m from one end.
• A ball is thrown horizontally from the top of a building, as shown in Fig. 2.1.
• An object of mass m travelling with speed v has a head-on collision with another object of mass m travelling with speed v in the opposite direction.
• Which statement about electromagnetic radiation is correct?
• A man standing next to a stationary train hears sound of frequency 400 Hz emitted from the train’s horn.
• When sound travels through air, the air particles vibrate. A graph of displacement against time for a single air particle is shown.

Question 22

Which of the following wave motions may be used to demonstrate the phenomenon of polarisation?

A a sound wave from a thunderclap

B a surface wave in a water ripple tank

C a stationary wave in an organ pipe

D a stationary wave on a stretched wire

Reference: Past Exam Paper – November 2015 Paper 12 Q25

Solution:

Answer: D. 

Polarisation cannot occur with a longitudinal wave as the direction of vibration is parallel to the direction of motion of the wave. Since sound is longitudinal, it cannot be used to demonstrate polarisation. [A incorrect]

If the movement of a wave is horizontal, after polarisation, the movement would be vertical. Surface waves on water demonstrate interference and diffraction easily but do not easily show polarisation. [B incorrect]

The movement of a wire can be horizontal or vertical (or a combination of the two). So, it can easily be used to demonstrate polarisation. [D is correct]