Question

A : The phase difference between any two points on a wave front is zero
R : From the source light, reaches every point on the wave front in the same time.

• A. Both A and R are true, and R is correct explanation of A
• B. Both A and R are true, and R is not correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

Answer: (A)

Both A and R are true, and R is correct explanation of A

A wave front is the locus of points having the same phase.
Thus statement A is true because the phase difference is zero as all points have same phase.
Statement R is true because a wavefront is composed of all points where the light reaches from the source in the same time.
As light takes the same time it has the same phase at all points on a wavefront and hence it correctly explains statement A.