43. In predicting the motion of tsunamis generated in the sea, and interacting with shoreline objects. A ripple tank is used to generate straight waves in region A that travel toward region B, which is separated from region A by a straight boundary. The frequency of the generator is 2.5 Hz, and the waves travel in region A with a speed of 15 cm/s. If the wave fronts in region A strike the boundary at 20", and the wave fronts in region B leave the boundary at 50". [4marks] (a) use Snell's law to nd the relative index of refraction between the two regions (2) (b) nd the wavelength in each region (2)