Explanation
(a) Differences between a sound wave and a radiowave



Sound wave
Radio wave


is a mechanical wave
is an electromagnetic wave


 is longitudinal
is transverse


has speed less than speed of light.
has speed equal to that of light


requires a material medium for propagation/cannot travel through vacuum.
does not require a material medium for propagation/can travel through vacuum.




  
(b) The vibrating tuning fork forces the table top to vibrate. The table top has a much larger area and is therefore in contact with a larger volume of air undergoing vibration. Hence, sound heard is amplified.
 
(c) Conditions necessary for:
 (i) production of stationary wave
- Two waves must be traveling in opposite directions.
- Incident and reflected waves must have the same frequency/wavelength.
- Incident and reflected waves must have equal amplitude.
- There must be superimposition.
- There must be a barrier
(ii) formation of interference wave pattern
- Two sources must be involved.
- The two sources must be coherent/have a constant phase difference as well as the same frequency and amplitude.
- The waves that are interfering must have the same amplitude
- The distance between the sources must be of the order of the wavelengths of the waves.
 (iii) total internal reflection
 - The wave must be traveling from a denser medium to a less dense medium
 - The angle of incidence of the wave in the denser medium must be greater than the critical angle for the medium.

 
(d)(i) Diagram

 Correct diagram
 (ii)  \(\frac{ Sin (A + dm)}{2}\)
 n =
  Sin (A/2)
 
  Sin (60 + 41)/2
          
  Sin (60/2)
  = 1.54

