What Am I Riddles

Question: I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter.

What am I?

Question: Everyday I stalk you all day long,
With every move you make, I never make one wrong.
I vanish twice a day with the sun's height and fall,
I will follow you anywhere,
even the bathroom stall.

What am I?

Question: I plow and plow, but never sow.

What am I?

Question: I used to fill rooms but now I'm a tower,
I can stay put or I can travel far.

What am I?

Question: I cannot hear or even see,
but sense light and sounds there may be.
Sometimes I end up on the hook,
or even deep into a book.

What am I?