From the statements below; the conditions for two waves to interfere are?

I. They should be identical
II. They should originate from the same source.
III. They should be coherent.
IV. They should be monochromatic.

A. I,II and III only
B. I, III and IV only
C. II, III and IV only
D. I, II, III and IV

Correct Answer:

Option B – I, III and IV only

Explanation

When waves come together they can interfere constructively or destructively. To set up a stable and clear interference pattern, two conditions must be met:

The sources of the waves must be coherent, which means they emit identical waves with a constant phase difference.

The waves should be monochromatic – they should be of a single wavelength.

Monochromatic wave refers to a wave with a single wavelength and frequency. It’s always only one colour. The waves may be coherent and noncoherent depending on the phase difference between the waves.