Two point sources, vibrating in phase, produce an interferencepattern in a ripple tank. if the frequency is increased by 20%, thenumber of nodal lines:

a) is increased by 20%
b) is increased by 40%
c) remains the same
d) is decreased by 20%
e) is decreased by 40%

option A

Explanation:

given,

frequency is increased by 20%

we know,

...........(1)

where

x_n is the perpendicular distance between the point the interference pattern is obtained,

L is the distance between the center of the two point sources

and λ is  the wavelength of light.

If the frequency is increased by 20%, then the number of nodal lines is increased by 20%.

From equation (1),we observe that the frequency is directly proportional to the number of nodal lines.

Hence, the correct answer is option A

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