Physics
Holography is a technique of

Recording a permanent, sharp two diimensional black and white or multicolour photograph
Recording a permanent three dimensional black and white photograph
Recording a permanent three dimensional multicolour photograph
Recording a permanent three dimensional photograph of a given single colour or a multicolour

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Physics
What is the principle of a ''Life Jacket"?

It provides oxygen to a drowning person
The person can sit on it like a raft
It decreases the volume of the person to keep him afloat
It increases the volume of the person to keep him afloat

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Physics
Energy in reflected light :

Does not depends on the angle of incidence
Increases with the increase in angle
Decreases with the increase in angle of incidence
Becomes maximum for angle of incidence equal to 45°

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