11-13: The diagram shows a standing wave formed on a stretched wire.

standing wave on a wire

11. How many nodes and antinodes are shown in the diagram?

  Nodes Antinodes
A
 1 2
B
 1 3
C
 3 2
D
 2 1

12. Which of the following correctly describes the movement of points Q and R compared to point P?

  Q R
A 900 out of phase with P 1800 out of phase with P
B In phase with P 1800 out of phase with P
C 1800 out of phase with P In phase with P
D 900 out of phase with P In phase with P

13. On the diagram above, what is this harmonic for the stretched wire and what is the distance between nodes ?

  Harmonic distance between nodes
A 1st λ/2
B 1st λ
C 2nd λ/2
D 2nd λ

14. A pipe is open at both ends. A standing wave is formed when air is blown across the pipe end. The first harmonic has a frequency of f and a wavelength of λ. The next harmonic that can be produced in the pipe with have a frequency of ...

  • A. f/3
  • B. f/2
  • C. 2 f
  • D. 3 f

15. A measuring cylinder containing some water is used to make an air column closed at one end.

A sound is produced using a tuning fork. The water level in the cylinder is adjusted until the air tube resonates and a louder sound is heard.

Using this method, the first harmonic is found when the air column is 10 cm long.

resonance of air column in measuring cylinder

What is the wavelength of the sound wave produced?

  • A. 2.5 cm
  • B. 5 cm
  • C. 20 cm
  • D. 40 cm

16. Microwaves of wavelength 1mm are directed at a 2 slits in a metal plates that are 10 cm apart. They are then observed at a screen 1 m away. The distance between the centre line and the first maximum point of intensity to the left of the centre line will be ...

  • A. 0.1 rad
  • B. 0.01 rad
  • C. 0.02 rad
  • D. 0.2 rad

17. A similar double slit experiment is carried out with red light waves and the interference pattern is recorded.

Which of the following would result in an increase in the separation of maximum points?

  • A. Using blue light of higher intensity
  • B. Using red light with a smaller gap between slits
  • C. using red light of higher amplitude
  • D. using blue light with a larger gap between slits

18. When light is incident on a flat glass surface ...

  • A. the reflected ray can be polarized parallel to the plane of the surface.
  • B. the reflected ray can be polarized perpendicular to the plane of the surface.
  • C. the reflected is not polarized.
  • D. the refracted ray can be polarized parallel to the plane of the surface.

19. A polariser produces a light beam of intensity 8 W polarised in a vertical plane. It then passes through an analyser aligned at 600 to the vertical. Given that cos(600)=0.5, what is the intensity of the transmitted beam?

  • A. 0 W
  • B. 2 W
  • C. 4 W
  • D. 8 W