Answer:
62.5 %
Explanation:
Let the initial intensity of unpolarized light is Io.
After first polariser the intensity of light becomes I'.
So, 
Now it passes through another polariser. The angle between the first polariser and the second polariser is given by Ф. The intensity is I''.
According to the law of Malus

Here, Ф = 30 degree

The percentage change in the intensity is given by

= 62.5 %
Answer:
Lubrication is used to reduce friction. It is generally used for moving machine parts. The lubricants are the substances which are used to reduce the friction which acts between two surfaces in contact, between which relative motion can occur.
The first question has the answer to your problem! I found the answer key!
34. The element would have 34 protons. Also 34 electrons.
Armature is the correct answer.