Q17 of 60 Page 1

A narrow beam PQ of white light is passing through a glass prism ABC as shows in the diagram.


(i) Write the name and cause of the phenomenon observed.


(ii) Where else in nature is this phenomenon observed?


(iii) Based on this observation, state the conclusion which can be drawn about the constituents of white light.

(i) The name of the phenomenon is Dispersion. The phenomenon of splitting of white light into its components colors while passing through a prism is known as Dispersion of light. The angle of refraction is different for different components of white light because of difference in speed of light when travelling through the medium. This results in the refraction of different colors of the light at different angles and thus results in formation of the spectrum.


(ii)This phenomenon of dispersion is observed when a rainbow is formed.


(iii)The conclusion which can be drawn from the constituents of white light is that white is light is composed of seven colors which are: Red, Orange, Yellow, Green, Blue, Indigo and White.


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15

A student wants to project the image of a candle flame on a screen 60 cm in front of a mirror by keeping the flame at a distance of 15 cm from its pole.

(i) Write the type of mirror he should use.


(ii) Find the linear magnification of the image produced.


(iii) What is the distance between the object and its image?


(iv)Draw a ray diagram to show the image formation in this case.

 16

Draw a ray diagram to show the path of the refracted ray in each of the following cases:

A ray of light incident on a concave lens is


(i) passing through its optical center.


(ii) parallel to its principal axis.


(iii) directed towards its principal axis

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 19

Elements forming ionic compounds attain noble gas configuration by either gaining or iosing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also give reason why carbon compounds are generally poor conductors of electricity.