Question
What makes things visible to us? Why cannot we see a book which is placed. $(a)$ Behind a wooden screen, and $(b)$ In a dark room?
✓
Answer
Light makes things visible to us. We see an object when light passing through it is reflected. We cannot see a book which is placed.
$a.$ Behind a wooden screen because the wooden screen is opaque so it does not allow light to pass through it.
$b.$ In a dark room because there is no light to be reflected by the book. Thus, due to no reflection, the book is not visible.
$a.$ Behind a wooden screen because the wooden screen is opaque so it does not allow light to pass through it.
$b.$ In a dark room because there is no light to be reflected by the book. Thus, due to no reflection, the book is not visible.
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