# Path difference of two series of monochromatic waves raech a point on screen

#### ling233

i was told that the path difference of two series of monochromatic waves raech a point on screen are same ... why is it so? can someone explain?

#### orsanyuksek

i was told that the path difference of two series of monochromatic waves raech a point on screen are same ... why is it so? can someone explain?
First of all, the formulation of your question needs to be updated: "... Monochromatic light waves with the same path difference reach the same point on a screen..."

Light is a transverse wave. If the point on the screen is hit by waves having the same path difference and wavelength (i.e., they are in phase and the light is monochromatic) they will hit onto the same point.

Consider a sin or a cos function. In phase, mean they have the same structure, that is the max and min position coincides. Besides, they are monochromatic, meaning the distance between two max is the same.

Under these circumstances, the point of arrival on the screen will be the same for both.

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