A spherical wave with a wavelength of 2.0 mm is emitted from the origin. At one instant of time, the phase at rrr = 4.0 mm is πradπrad. At that instant, what is the phase at rrr_1 = 3.5 mm ? Express your answer to two significant figures and include the appropriate units.

Complete Question

A spherical wave with a wavelength of 2.0 mm is emitted from the origin. At one instant of time, the phase at r_1 = 4.0 mm is π rad. At that instant, what is the phase at r_2 = 3.5 mm ? Express your answer to two significant figures and include the appropriate units.

The phase at the second point is  

Explanation:

From the question we are told that

    The wavelength of the spherical wave is  

    The first radius  is  

     The phase at that instant is  

     The second radius is  

Generally the phase difference is mathematically represented as

this can also be expressed as

So we have that

substituting values