(a) State two differences between a sound wave and a radio wave. (b) Explain why a vibrating tuning fork sounds louder when its stem is pressed against a ta...

(a)

(b)
The vibrating tuning fork forces the table top to vibrate. The table top has a much larger vibrating surface than the prongs of the fork and therefore sets a larger volume of air into vibration. More sound energy is transmitted to the air per second, so the sound is louder.

(c)

1. Production of stationary waves:
   • Two waves of the same frequency and equal or nearly equal amplitude must be present.
   • The waves must travel in opposite directions along the same line and superpose.
2. Formation of interference patterns:
   • The sources must be coherent, that is, have the same frequency and a constant phase difference.
   • The waves must overlap in the same region with equal or nearly equal amplitudes.
3. Occurrence of total internal reflection:
   • The wave must travel from an optically denser medium to an optically less dense medium.
   • The angle of incidence in the denser medium must be greater than the critical angle.

(d)(i) At minimum deviation, the path through the equilateral prism is symmetrical and the refracted ray is parallel to the base.

(d)(ii)
For an equilateral prism,

\[A=60^\circ, \qquad D_m=41^\circ\]

\[n=\frac{\sin\left(\frac{A+D_m}{2}\right)}{\sin\left(\frac{A}{2}\right)}\]

\[n=\frac{\sin\left(\frac{60^\circ+41^\circ}{2}\right)}{\sin\left(\frac{60^\circ}{2}\right)}=\frac{\sin 50.5^\circ}{\sin 30^\circ}\]

\[n=\frac{0.7716}{0.5000}=1.54\]

Therefore, the refractive index of the glass is \(1.54\).