Four traveling waves are described by the following equations, where all quantities are measured in si units and y represents the displacement. i: y = 0.12 cos(3x - 21t) ii: y = 0.15 sin(6x + 42t) iii: y = 0.13 cos(6x + 21t) iv: y = -0.27 sin(3x - 42t) which of these waves have the same period?

Explanation:

Wave 1,

Wave 2,

Wave 3,

Wave 4,

The general equation of travelling wave is given by :

The value of will remain the same if we take phase difference into account.

For first wave,

For second wave,

For the third wave,

For the fourth wave,

It is clear from above calculations that waves 1 and 3 have same time period. Also, wave 2 and 4 have same time period. Hence, this is the required solution.