When the light from two lamps falls on a screen, no interference pattern can be obtained. Why is this?
Correct answer: C. The light from the lamps is not coherent.
- A. The lamps are not point sources.
- B. The lamps emit light of different amplitudes.
- C. The light from the lamps is not coherent.
- D. The light from the lamps is white.
Explanation
When light from two separate lamps falls on a screen, interference patterns typically do not form because the light from each lamp is not coherent. In order to observe interference patterns, the light sources need to be coherent, which means that the light waves emitted by the sources have a constant phase difference between them.
This question appeared on the ETEA MDCAT 2013 paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Superposition and Interference
Superposition states that overlapping waves produce a resultant displacement equal to the algebraic sum of their individual displacements. Interference covers constructive and destructive interference, phase difference, path difference, coherent sources, and conditions for maxima and minima. It differs from diffraction, which involves spreading around openings or obstacles.
Practise Waves
1,281 free Waves MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Superposition and Interference questions
The colors in the soap bubble are due to:
If a green light in a Young double slit experiment is replaced by monochromatic orange light of the same intensity, Then:
Two coherent monochromatic sets of waves will interfere constructively in the region of superposition only if the path difference between them is :
Monochromatic light passes through two parallel slits in a secreen and falls on a place of film. The patteren produced is an example of:
Using monochromatic light, interference fringes are produced on a screen placed a distance D from a pair of slits of separation a. The separation of the fringes is x. Both a and D are now doubled. What is the new fringe separation?
The colour of thin films is a result of: