What are Polaroids?

What is a polaroid?

What do you mean by the term crossed polaroids?

What is a tissue? What are its kinds?

What are radio-isotopes? What are their applications?

Two polaroids are placed at 90^@ to each other and the transmitted intensity is zero .What happens,when one more polaroid is placed betwen these two,bisectiing the angle between them.How will the intensity of transmitted light vary on further rotatint the third polaroid?

Write two uses of polaroids?

Two polaroids are placed at 90^@ to each other.What happens,when(N-1) more polaroids are inserted between them?Their axis are equally spaced.How does the trnsitted intensity behave ffor large N?

Light from an ordianry source(say a sodium lamp) is passed through a polaroid sheet P_1 .The transmitted light is then made to pass through a second polaroid sheet P_2 ,which can be rotated so that the angle (theta) betwen the two polaroid sheets varies from 0^@ to 90^@ .Show graphically the variation of he intensity of light transmitted by P_1 and P_2 as a function of the angle theta .Take the incident beam intensity as I_0 . Why does the light from a cleear blue portion of the sky,show a rise and fall on intesnity,when viewed through a polaroid ,which is rotated?