How will you use two identical prisms so that a narrow beam of white light incident on one prism emerges out of the second prism as white light? Draw the diagram.

Light coming from the sun is white light and contains seven colours.

What is the role of the pupil in a human eye?

Which of the following is not a primary color of light?

$A$ narrow beam $PQ$ of white light is passing through a glass prism $ABC$ as shown in the diagram.
Trace it on your answer sheet and show the path of the emergent beam as observed on the screen $DE$.
$(i)$ 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.

$A$ student cannot read properly from the blackboard while sitting on the front desk in a large classroom. However,he can read clearly while sitting on the last desk of the classroom.
$(a)$ Draw ray diagrams to illustrate the formation of the image of the blackboard writing by his eye lens when he is seated at the $(i)$ front desk,$(ii)$ last desk.
$(b)$ Name the defect of the eye from which the student is suffering.
$(c)$ Name the type of lens that would enable him to see the blackboard writing clearly when seated at the front desk. Draw a ray diagram to illustrate how this lens helps him to see clearly.