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ICSE Class 8 Answered

Define dispersion of white light through a prism, its recombination and composition of (VIBGYOR). Formation of primary/secondary rainbow    
Asked by mandalnikhil0740.8sdatl | 02 May, 2020, 05:56: PM
answered-by-expert Expert Answer
a) Dispersion of light is the phenomenon of splitting of white light into its constituent seven colours on passing through a glass prism.  
b) When white is passed through a prism, dispersion of white light into seven constituent colours occurs as the lights of different colours bend through different angles while passing through the prism. This happens due to the difference in the velocities of different colours through the prism. i.e the refractive index of the glass is different for different colours. When white light is passed through the first prism, it disperses the white light into seven colours. The second identical glass prism kept upside down recombines these rays into the white light. This recombination occurs due to the reverse refraction produced by the second prism kept upside down with its refracting sides parallel to each other. On the other hand if the second prism is kept just like the first prism, then no recombination of dispersed light occurs. 

- Recombination Prism is the prism which enables the recombining of the dispersed ray of light (VIBGYOR) into the ray of white light.
- The bending of light or the refraction phenomenon is used to disperse a white light into VIBGYOR by first prism and the recombination prism due to its optical arrangement recombines VIBGYOR into the white light which was originally incident n the first prism.



Answered by Shiwani Sawant | 03 May, 2020, 12:59: AM
ICSE 8 - Physics
Asked by pateljanvi7028.8sdatl | 27 May, 2020, 05:29: PM
ICSE 8 - Physics
Asked by mandalnikhil0740.8sdatl | 02 May, 2020, 05:56: PM
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