Interference effects are possible due to superposition of two or more waves in a certain region of space in case of:

Explanation:

Interference:

• The combination of two or more electromagnetic waveforms to form a resultant wave that may have greater, lower, or the same amplitude is called interference.
• Interference occurs for both transverse (ex- light wave) and longitudinal waves (ex- sound wave).

Additional Information

Interference of light wave 

• When two light sources from different coherent sources meet together, then there is a distribution of energy and it is disturbed by each other. This superposition of two light waves is called the Interference of light waves.
• The interference of light obeys the law of conservation of energy as the light energy which disappears in areas of destructive interference appears in the areas of constructive interference, thus, the average intensity of light remains constant. Therefore, the net energy remains conserved.
• Interference of  is explained by the wave nature of light
• An optical flat uses the principle of interference of light to measure differences in heights of slip gauges or flatness
• Constructive and destructive interference: 
  • ​When the waves of the light meet at a point with the same phase then the constructive wave is formed. Similarly when waves of opposite phases meet at a point then it creates a destructive interference pattern.​
• Constructive interference occurs when the crest of one wave falls on the crest of other wave or the trough of one wave falls on the trough of the other wave.
• The resultant intensity due to constructive interference is, therefore, maximum.